C-130 Broad Area Review
(January 1998)

TABLE OF CONTENTS

Tasking From The Secretary of the Air Force

The report you are about to read answers the Secretary of the Air Force’s direction to conduct a BAR of C-130 flight safety. Our goal was to make it understandable, by explaining or eliminating as much service jargon as possible. It represents our team’s review of C-130 aircraft systems, training programs, maintenance activities, and flying operations.

The Secretary of the Air Force, responding to a request from members of the United States Senate, tasked the Acting Chief of Staff of the United States Air Force to conduct a BAR of C-130 flight safety, addressing the missions and environments in which it flies, and its safety history. In addition, the Secretary directed the team to look at the King 56 incident to make certain all potential causes and contributing factors were properly considered, and to ensure that everything appropriate was being done to enhance C-130 flight safety.

Executive Summary

Team Composition

In response to the Secretary of the Air Force’s (SECAF) direction to form the team, the team chief selected a group of individuals with a broad background of experience in the C-130 weapon system. Representing a combined total of 45,000 flight hours and over 235 man-years experience with the aircraft, the team included operators and maintainers from the using commands (including the Air National Guard and Air Force Reserve Command), Air Force Safety Center, Air Force Materiel Command and Headquarters Air Mobility Command. There were members from logistics, operations, and the National Transportation Safety Board. Representatives of the aircraft’s manufacturer and major component suppliers (i.e., engine and propeller manufacturers) served as advisors to the team.

Approach

Our approach was simple and direct--get the right experts, get the facts (firsthand whenever possible, from the field operators and maintainers), determine safety issues within C-130 operations and maintenance (including training and aircraft systems, and aircraft safety data) identify possible scenarios for King 56, evaluate each, then report. To execute that approach, the BAR traveled to sixteen C-130 operating and maintenance locations across the country (Little Rock AFB, AR; Pope AFB, NC; Duke Field, FL; Hurlburt Field, FL, Moody AFB, GA; Keesler AFB, MS; Harrisburg ANG, PA; Warner-Robins ALC, GA; Kirtland AFB, NM; Davis-Monthan AFB, AZ; Youngstown ANG, OH; Dobbins AFB, GA; Lockheed-Martin Corporation, Marietta, GA; Moffett Field, CA; Schenectady, NY; and Portland ANG, OR), spoke with literally hundreds of crew members and maintainers, performed and analyzed tests, and read reports. The BAR also took leads from a toll free number that the BAR established to help us gather the information the BAR needed.

Fleet Safety Record

The team came away from this review convinced that the C-130 has been, and remains, a very safe and dependable aircraft. The team became increasingly aware of crew member suspicions that the aircraft’s synchrophaser (an electronic device used to synchronize the propellers and phase the passing of their blades as they turn so as to reduce propeller-induced noise and vibration), was to blame for King 56 and other engine power loss incidents. The team found that the internal failure of the synchrophaser was rarely the cause of the incidents examined (2 of 71). When involved, it turned out to be only a contributory factor to the problem, usually as a result of faulty signals fed from other systems, or by electromagnetic interference (EMI).

The BAR examined the C-130 fleet safety record and found that, in almost 25 million flight hours worldwide, there had not been a recorded instance before the King 56 accident where all four engines quit running in flight. The team reviewed data from multiple sources (including: contractor manuals, aircraft technical orders, safety and accident reports, and aircrew and maintenance interviews) and analyzed the information, as well as aircraft test results, at considerable length.

In the case of King 56’s uncommanded power-loss, the team believes the most likely explanation remains fuel starvation, due to one of several possible causes, each of which the BAR has evaluated in detail within the body of the report. Although the BAR believes it was fuel-related, no single specific cause could be conclusively determined. In this report, the BAR presents the scenarios that explain how this loss of fuel to the engines might have happened. The facts the BAR established, combined with test results referenced under each scenario, enabled the BAR to narrow the focus to four likely scenarios.

Action Taken

The Air Force published a safety supplement to change the flight manual emergency procedures for dealing with four-engine or multiple engine power-loss. Prior to publishing this report, the team drafted this bold face procedure which crews must commit to memory and use immediately in such an emergency to improve their odds of solving the problem before it becomes unrecoverable. The crews exposed to this procedure overwhelmingly approved of it and were quick to provide feedback on how to improve upon it.

Recommendations

The BAR’s recommendations, listed below, are divided into three categories: general, C-130 specific, and King 56 salvage.

A. General Recommendations:

1. Lead Command Operating Instruction: The Air Force should review and update the existing lead command operating instruction to:

a. Fully reflect changes which have occurred since the CONUS theater airlift fleet transferred from Air Combat Command to Air Mobility Command.

b. More fully define the lead command’s leadership role and its responsibilities, particularly with respect to configuration control (making certain that cockpit instrumentation and aircraft modifications are standardized across a fleet of like aircraft to facilitate standard operating and maintenance procedures). This leadership role should extend to cover generic operational issues as well.

c. Better define the lead command’s authority to enforce configuration control and the accountability of other commands to the lead’s direction.

d. Empower the lead command and properly resource the lead and other user/supporting commands to enable them to:

1. Update, consolidate and standardize aircraft flight manuals and operating guidance to assure crews have current procedures and performance data.

2. Do the same for maintenance manuals to assure maintainers have the up-to-date information they need to properly maintain the aircraft.

2. Air Force, Federal Aviation Administration, and National Transportation Safety Board Standardized Flight Data Recorder Parameters: DFDR performance limitations severely hampered the King 56 investigations and this review. The Air Force should consider the Federal Aviation Administration and the National Transportation Safety Board guidelines and experience in arriving at a standardized set of digital flight data recorder flight parameters. This would ensure that essential flight data is captured for evaluation in future incidents and accidents.

3. Ditching & Bailout Procedures: The Air Force should review ditching and bailout procedures. As part of this effort, the Air Force should:

a. Conduct an analysis of world-wide ditching events. That data should be used to update and standardize all flight manuals with an accurate discussion of ditching survivability and techniques.

b. Review the information concerning bailout in the flight manuals for consistency between models of the same aircraft, and revalidate the accuracy of the information provided to the crews.

c. Establish a requirement for crews to review these procedures on the first leg of each over-water mission, in order to maintain reasonable familiarity with these procedures.

d. Establish a standard life support equipment requirement, appropriate for the aircraft’s missions, for each mission design series C-130 and equip each for that requirement.

B. C-130 Specific Recommendations

The team made the following recommendations based upon its BAR of C-130 missions, operating environments, and the fleet’s flight safety record (with particular emphasis placed on the 71 incidents the BAR examined involving uncommanded power reduction):

1. C-130 Technical Orders: A total of 487 of the Air Force’s 627 C-130 technical orders currently have an inordinate number of supplemental page inserts and are in need of a complete rewrite to incorporate the new information into the body of the text. For several years there has not been sufficient funds available to complete the rewrites. This important issue is broader than just the C-130 alone and is under review Air Force-wide. It will require a significant investment, over $20 million and approximately two years to fix the C-130 alone, using current manpower levels to correct. The Air Force should fully fund this action, as well as new initiatives underway to convert USAF technical manuals from the old, expensive and time-consuming paper format to the newer digital format. New CD-ROM technology offers many benefits, including a reduction in the annual $2.5 million cost of maintaining our T.O.s. This conversion faces many obstacles, including the cost of conversion as well as training and equipping field units to handle electronic data rather than paper.

2. EC-130 Commando Solo II Mission Evaluation: Until replaced with newer, more capable C-130s, the Air Force should reevaluate and closely monitor the EC-130 Commando Solo II mission.

C. King 56 Salvage

The BAR recommends the Air Force recover selected wreckage from King 56. The components of greatest interest are: the wing section, the fuselage tanks, and the cockpit fuel quantity gauges. These items could answer many open questions and provide additional information concerning the various fuel-related scenarios. While the exact cause of the King 56 mishap may never be known with absolute certainty, this wreckage could reveal a probable cause and refute many scenarios. The most compelling reason to obtain additional wreckage is the possibility that evidence might be found which points to an unknown new scenario.

Section 1.0

C-130 Operating Environments and Missions

1.1 Background

1.1.1 Since its introduction into the Air Force inventory in 1955, the C-130 has served in a variety of operating environments and missions. From the polar regions to the tropics, this aircraft has delivered personnel, equipment, and supplies by a variety of means to locations all over the planet. Over 2,000 aircraft support the United States and its Allies’ military operations, as well as numerous commercial operations.

1.1.2 There are few environments this aircraft has not operated in. It has served as a launch platform for remotely piloted vehicles, and as a recovery platform for both personnel and data packages. It routinely penetrates hurricanes, delivers ordnance, provides combat communications links, facilitates rescues on land or at sea, services our remote stations at the North and South Pole, refuels aircraft, and broadcasts radio and television messages when the mission requires. In the late 1950s, it provided a good deal of aerial photography for cartography used to this day in the United States. It has been an air ambulance, and a deliverer of relief supplies to refugees, and a transporter of refugees to safety around the world. It has fought forest fires from California to Indonesia. By far, it’s most often seen as a theater airlifter, either air dropping or air landing troops, equipment, and supplies to wherever they are needed.

1.1.3 The aircraft used in this theater airlift role typically operate in the low altitude regime, flying a few hundred feet above the ground with their crews navigating by a combination of pilotage, self-contained navigation systems, global positioning systems, and "dead reckoning." Flying a series of carefully developed course lines, designed to avoid known threats while ingressing to their target drop or landing zones, these aircraft typically stay low until their destination, rising only to drop their paratroops or pallets, or coming in for an "assault" (short field, i.e., 3,000 foot long airstrip) landing. They exit the same way. Equipped in some cases with Adverse Weather Aerial Delivery Systems (AWADS) or their equivalent, they may drop their loads without ever seeing their target visually, but with impressive and reliable accuracy. Traveling singly or in formation, in daylight or on night vision goggles in blacked-out configuration, they deliver the goods where needed.

1.1.4 While the low-level portion of the flight exposes them to hazards from bird strikes to small arms, anti-aircraft artillery fire, and Surface to Air Missiles (SAMs), it is the pass over the drop zone, or the time spent getting into and out of the assault strip, that is probably the most dangerous for the aircraft and crew. Relatively high in the air and slow at that point, here they are most vulnerable to ground fire. A large portion of the C-130 force trains for this kind of operation daily.

1.1.5 Not always used in the combat delivery mode, the basic airlift version of the C-130 has an intercontinental range, allowing it to carry a number of pallets of cargo, or up to 92 passengers. This range, and the aircraft’s versatility, made it a logical candidate for a number of modifications to support a variety of special missions.

1.2 C-130 Operating Environments and Missions

1.2.1 The C-130 is arguably the most versatile aircraft in the Air Force inventory. Currently 52 units in the active force, Air National Guard and the Air Force Reserve Command fly the aircraft in the combat aerial delivery mode alone.

1.2.2 Combat Aerial Delivery: The most common mission is called combat aerial delivery, or "CAD" for short. This term refers to delivering cargo by landing at an airfield (called "airland") or dropping it by parachute (called "aerial delivery"). The airland mission involves operating the aircraft into airfields worldwide, from large, busy commercial airports like Chicago, O’Hare, to small, isolated, unimproved dirt landing zones bulldozed and hacked out of almost anyplace, which can be as short as 3,000 feet long. The aerial delivery element of CAD involves air dropping personnel and equipment following ingress. This can be done as a single aircraft or as part of a large formation. Airplanes get to the drop zone by making use of either visual procedures or in Instrument Meteorological Conditions (in weather, or "IMC" and flying on instruments) using Station Keeping Equipment (SKE). SKE depicts the other airplanes within a formation, and tells the pilot continuously where to fly to maintain the exact desired position, both vertically and horizontally, within the formation. The Air Force flies this mission at night as well, at a minimum altitude of 500 feet above ground level (AGL), using visual procedures and night vision goggles ("NVGs" light up the portion of the ground or sky the pilot is looking at by use of light amplification).

1.2.3 Rescue: In addition to flying typical combat aerial delivery missions, rescue units fly three other missions. The first is aerial refueling helicopters. These refuelings are conducted at altitudes as low as 1,000 feet and are done both day and night, with night missions using NVGs. The second mission involves the deployment of life rafts and other materials to survivors at sea, by conducting air drop operations from altitudes of 150 feet above the water during the day and 500 feet above the water at night. A third mission is search. Rescue crews routinely practice overwater and overland searches from altitudes as low as 500 feet. Over the years, rescue units have developed a capability to insert rescue forces long range into hostile territory. Their range and refueling capabilities enable them to ferry rescue helicopters great distances for recovery of these inserted rescue forces

1.2.4 Special Operations: Crews flying Special Operations aircraft fall into several categories. Some fly aircraft in a rescue role similar to the rescue mission discussed above. Another Special Operations mission is to fly combat aerial delivery-like operations but in a more demanding environment. These aircraft are equipped with more precise navigation equipment, allowing lower altitudes during night operations. They are also capable of landings on unlit landing zones and aerial refueling in flight (as the receiver aircraft, thus extending their range).

1.2.4.1 When operating at night, gunships use sensitive optical and electronic sensors to detect ground activities and direct a wide array of weapons to attack those targets.

1.2.4.2 "Commando Solo II" is the name for the psychological warfare mission flown by one Air National Guard unit. This mission involves orbiting near, or in some cases over, enemy territory to broadcast information or jam enemy operations. They operate at extremely high operational weights and can be refueled while airborne. These aircraft have the highest empty gross weights of the fleet, owing to the broadcast equipment they carry. When combined with their relative age, the requirement to refuel to near emergency gross weight limits for deployments on operational missions, and the high potential for Radio Frequency Interference (RFI) induced electrical problems, these factors identify this mission as one associated with marked higher risk than others.

1.2.4.3. "Senior Scout" is another variant that serves as an intelligence-collection platform. The mission is accomplished by both active and ANG units.

1.2.5 Polar Operations: One ANG unit flies C-130s equipped with skis for landing on snow and ice. This unit is principally responsible for support of Arctic and Antarctic operations. These operations expose both aircraft and crews to the environmental challenges of extreme cold, variable weather and substandard landing zones.

1.2.6 Compass Call/Airborne Command, Control and Communications (ABCCC): These two missions have different operational roles but operate in basically the same environment. The aircraft serve as a platform for communications activities. Operating in a "stand off mode" that generally places them adjacent to the battle area but not directly in or over it, their operational environment is relatively benign. The mission’s chief drawbacks are its requirement to operate in proximity to unfriendly nations, its high aircraft operational weights, and the need to remain on station for extended periods of time.

1.2.7 Weather: The weather aircraft and crews, assigned to Air Force Reserve Command (AFRC), are used for storm tracking and evaluation. By flying into hurricanes and taking atmospheric readings at various locations within the storm, they obtain data critical to improved weather forecasting. The principal dangers associated with this mission are weather related turbulence and lightning.

1.2.8 Other missions: Several units maintain a limited capability to conduct unique operations.

1.2.8.1 Aerial Spray: These AFRC crews conduct low-level operations in rural and, occasionally, urban areas to dispense pesticides, oil dispersing agents and defoliants. These operations are conducted at altitudes as low as 100 feet and speeds of 125 knots. This operation is only conducted in daylight and in good weather.

1.2.8.2 Modular Aerial Firefighting System: This mission, flown by both Air National Guard and Air Force Reserve Command crews, involves dropping fire retardant foam on forest fires. This operation is conducted at altitudes of 150 feet, 130 knots. The greatest demand on the crews and aircraft is operation in heavy smoke that reduces visibility in rugged terrain.

1.2.8.3 Space Shuttle Support: One rescue unit has the principal responsibility to support rescue efforts for every NASA Space Shuttle launch. The HC-130 serves as a command-and-control platform, a jump platform, and an air refueling platform for rescue helicopters.

Section 2.0

Aircraft Systems

2.1 Introduction

2.1.1 The team reviewed all major C-130 aircraft systems with specific emphasis on safety-related issues or deficiencies that exist. This section includes a description of each system, safety issues that surfaced during the review, and the corrective actions taken or that needed to be taken to mitigate the issues or deficiencies noted.

2.1.2 Special emphasis was placed on possible causes of uncommanded power reductions. The team accelerated the Failure Modes, Effects and Criticality Analysis (FMECA) of the synchrophaser and required specific ground and flight tests to be conducted.

2.1.3 Prior to the establishment of the BAR, C-130 systems were in the process of being analyzed through the FMECA process to uncover hypothetical failure modes. It analyzes design and performance data to determine how the targeted systems perform their intended functions, as well as whether those systems have unrecognized effects or synergistic interactions with related systems. It then extrapolates the relative severity, probability, and worse-case impact of each identified failure mode. More simply put, each piece or part of the aircraft’s systems are being evaluated to determine what its function is, how many different failure modes each piece or part can have, and how each failure mode effects both the systems and the aircraft as a whole.

2.1.4 The aircraft fuel system was subjected to ground and flight tests at Edwards AFB. The test objectives used were designed to see if the system could theoretically function in ways not previously recognized. These objectives took into account both systems and aircraft design, as well as human factors. The team felt the dual approach of systems analysis and aircraft ground and flight tests was the best way to evaluate which system (or combination of systems) malfunctioning can result in a power-loss.

2.2 Structures

2.2.1 The airframe subsystem is the "skeleton" of the aircraft and supports various flight and landing "loads" (i.e., the term used for stresses put on the airplane on the ground or in flight). The airframe subsystem is comprised of four major structural elements: the wing, fuselage (i.e., the body of the aircraft which actually carries the passengers and cargo), empennage (the "tail section" of the aircraft), and the landing gear. The primary purpose of the wing is to generate the lifting force needed to hold up the fuselage in flight. The fuselage structure must also support cargo and pressurization load stresses, as well as the load stresses being transmitted from the wings and from the empennage. The empennage structure transmits and carries the same type of load stresses as the wings, except that they are smaller and serve to keep the airplane stable around the vertical and lateral axes in flight. Last, the landing gear absorb the shock and vibration load stresses that occur as a result of taxiing, takeoff, and landing. During the BAR’s review of C-130 flight safety, they noted no flight safety concerns related to the aircraft’s structure that were not being addressed by the C-130 SPO.

2.3 Propulsion (Propellers & Engines)

2.3.1 The C-130 is powered by either four T56-A-7B or T56-A-15 engines. The major components of the engine are the power section, extension shaft assembly, and the reduction gear assembly.

2.3.2 Power Section. The power section of the engine has a single entry, 14-stage axial-flow compressor, a set of 6 combustion chambers, and a 4-stage turbine. Mounted on the power section are an accessories drive assembly and components of the engine fuel, ignition, and control systems (the engine fuel system is described in detail later in this section). The ignition system is a high-voltage, condenser discharge type, consisting of an exciter, two igniters, and control components. The ignition system is powered by the essential DC bus. The system is controlled by the speed-sensitive control through the ignition relay, which turns it on anytime the engine RPM is between 16 and 65 percent. A manifold bleeds air from the compressor for airplane pneumatic systems. Anti-icing systems prevent accumulation of ice in the engine inlet air duct and the oil cooler scoop. Fuel flows into the combustion chambers and is burned, increasing the temperature and energy of the gases. The gases pass through the turbine, causing it to rotate and drive the compressor, propeller, and accessories.

2.3.3 Extension Shaft Assembly. The extension shaft assembly consists of two concentric shafts and the torquemeter components. The inner shaft transmits power from the power section to the reduction gear assembly. The outer shaft serves as a reference shaft for the torque indicating system.

2.3.4 Reduction Gear Assembly. The reduction gear assembly reduces the high speed of the engine (13,820 RPM) to the lower speed needed by the propeller (1,020 RPM). The reduction gear contains a reduction gear train, a propeller brake, an engine negative torque control system, and a safety coupling. The reduction gear train is in two stages, providing an overall reduction of 13.54 to 1 between engine speed and propeller speed.

2.3.5 Related Deficiencies and Concerns:

DEFICIENCY: In the event of total AC electrical failure or flameout of all four engines in-flight, the engine ignition system cannot be powered from the aircraft battery.

ON-GOING RESOLUTION: The BAR supports development and implementation of a C-130 modification which would allow the ignition system (essential DC bus) to be powered from the aircraft battery in-flight in the event of total AC electrical failure or flameout of all four engines.

2.3.6 Each engine is equipped with a Hamilton Standard four-blade, electro-hydromatic, full feathering, reversible-pitch propeller. The propeller operates as a controllable-pitch propeller for throttle settings below FLIGHT IDLE and as a constant-speed propeller for throttle settings of FLIGHT IDLE or above. The major components of the propeller system are the propeller assembly, the control system, the synchrophasing system, and the anti-icing and de-icing systems.

2.3.6.1 Propeller Assembly. The propeller assembly consists of the actual propeller blades, the barrel assembly (which retains the blades and also contains the pitch lock assembly), and the dome assembly (which contains the pitch changing mechanism and the low pitch stop assembly).

2.3.6.2 Control Assembly. The control assembly is mounted just behind the propeller assembly but does not rotate. It contains the oil reservoir, pumps, valves, and control components which supply the pitch changing mechanism with hydraulic pressure to change the propeller blade angle. All mechanical and electrical connections necessary for propeller operation are made through the control assembly. The mechanical connections are for the engine control system and the negative torque signal (NTS) system. The electrical connections are for oil level indications, pulse generator coil, auxiliary pump motor, synchrophasing system, NTS and feather switches, anti-icing and deicing systems and the electrical feathering system. The valve housing is the "brain" of the propeller and contains the fly weight speed sensing pilot valve, feather valve, feather solenoid valve, and feather actuating valve. The speed of the propeller is controlled by the fly weight speed sensing pilot valve. The valve is controlled by the mechanical action of the flyweights opposing the force of the speeder spring. Under normal conditions the propellers are rotating at 100% of its design speed (1,020 RPM) or "on-speed". When the propeller is in an on-speed condition, the metered hydraulic pressure equals that required to maintain the required blade angle. When an overspeed condition occurs, the fly weight force overcomes the speeder spring force, and the pilot valve moves to port hydraulic pressure to increase the blade angle which causes the propeller to slow down. If the propeller slows down below the governed speed, the force of the speeder spring overcomes the force exerted by the fly weights, and the pilot valve moves to port hydraulic pressure to decrease the blade angle, which allows the propeller to increase speed. The action of the fly weight speed sensing pilot valve is the primary means of controlling the RPM of the propeller and is always attempting to maintain 100% (1,020 RPM) in flight.

2.3.6.3 Synchrophasing System. The propeller mechanical governor will hold a constant speed in the flight range, but throttle changes will cause the governor to overspeed or underspeed slightly while trying to compensate for the change in power. The synchrophasing system assists the mechanical action of the fly weight speed sensing pilot valve. The synchrophaser provides speed stabilization, throttle anticipation, and synchrophasing. The speed stabilization circuit stabilizes the mechanical governor when the propeller governor control switch is in the NORMAL position by sending a signal to the speed bias servo motor to change the speeder spring compression. Throttle anticipation stabilizes the propeller speed during rapid movement to the throttle when the propeller governor control switch is in the NORMAL position. Rapid throttle movement sends an amplified signal to the speed bias servo motor to change speeder spring compression. The synchrophasing system acts to keep all the propellers turning at the same speed, and it maintains a constant rotation position relationship between the blades to decrease vibration and to lower the noise level. The system uses either the number 2 or the number 3 engine as the master engine, and relates the blade position of the other three propellers to the master. The blade position of a slave propeller is changed by moving the pilot valve to increase or decrease the speed of the engine. The synchrophasing circuit determines blade position by comparing an electrical pulse generated by each slave propeller to a pulse from the master propeller. In normal governing and synchrophaser modes, the synchrophaser can only change the RPM of the propeller approximately 2.5%. Mechanical stops in the propeller valve housing prevent the RPM from decreasing more than 4% (below 96%) or increasing more than 6% (above 106%).

2.3.6.4 Anti-Icing and Deicing System. The propeller anti-icing and deicing system is made up of resistance-type heating elements which are incorporated on the leading edge and fairing of each blade and the entire spinner assembly for anti-icing. Continuous anti-icing heaters cover the front portion of the spinner assembly and the entire afterbody assembly. Cyclic deicing heaters cover the remainder of the spinner front section, the spinner rear rotating section, the spinner plateaus, and the blade leading edge and fairing. Power from the aircraft electrical system is transmitted through a brush housing assembly through rotating sliprings to the anti-icing and deicing elements.

2.3.7 Rollback. The term "rollback" has been used for several years to describe an event in which multiple engines experience a sudden, relatively small reduction in engine speed, uncommanded by the crew and with no prior indications of engine problems such as fluctuating fuel flow or turbine inlet temperature (TIT). Rollbacks have historically been associated with the synchrophaser or electrical system problems, such as low voltage or electromagnetic interference (EMI), which can affect synchrophaser operation.

2.3.7.1 During a rollback, affected engines respond essentially simultaneously. Some rollbacks are momentary, (i.e. the RPMs pull back for a few seconds) and then recover without crew intervention. Some rollbacks persist and do not recover until the corrective procedures are performed. However, in both instances, the engines exhibit relatively stable operation except for momentary torque and RPM changes. In other words, the torque and RPM changes are not accompanied by significant variations in fuel flow and TIT.

2.3.7.2 Since the synchrophaser has no direct control over the power output of the engine and has such limited RPM control authority, it cannot by itself cause large, unstable, erratic variations in fuel flow, TIT, torque, etc. These are indications that something else is affecting the power output of the engine, such as a fuel system problem. However, if the engine selected as "master" (either number 2 or number 3 engine) is experiencing problems for any reason which reduces its power enough to affect its RPM, the other three "slave" engines will be driven by the synchrophaser into small variations, as it tries to keep them in phase with the malfunctioning engine. If this should happen, the RPMs of the three remaining engines will only be driven down by a maximum of 2.5%.

2.3.7.3 Ground tests during earlier synchrophaser investigations confirmed that erroneous output signals to the propeller governors had little to no effect on actual engine power output. One possibility tested was that those electrical disturbances known to produce erroneous synchrophaser signals could also independently affect the temperature datum (TD) amplifier, causing uncommanded power reduction unrelated to synchrophaser RPM reduction. The laboratory instruments revealed these electrical disturbances did not effect actual engine power output, but did produce erroneous aircraft instrument readings.

2.3.7.4 Crew reactions to rollbacks and power fluctuations have varied considerably. Some report that the event is no more than a mild annoyance; others say it really gets their attention. However, the measurable effect of a rollback on the flying qualities of the aircraft has proven to be very small. Rollbacks have been extensively investigated, both by gathering data on actual incidents and by duplicating the events during engine test cell runs and flight tests. As a result, rollback causes have been identified and corrective actions implemented which have dramatically reduced both the frequency and the magnitude of the events.

2.3.7.5 Engine rollbacks can be caused by internal synchrophaser failure, resulting in erroneous output signals. Since the synchrophaser was redesigned (from vacuum tube to solid state technology), this is now a rare event. The new synchrophasers contain safeguards designed to limit the magnitude of erroneous signals if the unit did fail. Although reliability increased with the solid state units, they did exhibit vulnerability to electrical power disturbances and EMI, or "noise," from other aircraft electronic systems, notably the high frequency (HF) radio. Several equipment modifications have been made which have been effective in reducing the frequency and impact of these events. Some wires have been shielded, components redesigned and additional components installed to stabilize the synchrophaser system. As shown in the failure history, (see Figure 5-3), these changes have been effective in reducing rollback occurrence. A continuing problem is the susceptibility of the aging synchrophaser wiring bundles to EMI.

2.4 Fuel System

2.4.1 Aircraft Fuel System. The primary purpose of the fuel system is to efficiently distribute fuel to its engines. There are four main fuel tanks and two auxiliary tanks located in the wings. The main tanks are numbered 1 through 4, from left to right. The auxiliary tanks are located in the center wing. Two external tanks are installed on pylons under the wings (C-130E/H aircraft and their variants). Tanker/rescue and other special mission aircraft are also equipped with one or two internal fuselage tanks. The fuel tanks are vented and fuel is displaced by ambient air as the tanks empty (fuel is displaced by cabin air for the fuselage tanks). Fuel management is controlled by the flight engineer through the overhead fuel control panel located on the flight deck (see Figure 2-1). C-130 tanker aircraft have an additional air refueling panel which contains the controls and gauges for the fuselage tanks that is also controlled by the flight engineer (see Figure 2-2). By positioning the switches on the panel(s), the flight engineer can control how fuel is used during flight as well as manage refueling and dumping operations.

 

Figure 2-1: Typical Overhead Fuel Panel, located on the cockpit ceiling between the pilots

 

2.4.1.1 All fuel tanks are interconnected by two pipes or "manifolds". One is called the crossfeed manifold, the other is the refuel/dump manifold. These two manifolds can also be interconnected. By selectively opening or closing various valves and activating or deactivating pumps, fuel can be pumped from any tank to any engine the flight engineer requires.

2.4.1.2 When each engine is fed by its corresponding fuel tank (number 1 tank supplies fuel to the number 1 engine, etc.), it is described as "tank-to-engine" configuration. This is the normal fuel system configuration used for take-off and landing (see Figure 2-3). The "tank-to-engine" configuration requires the partitioning of the crossfeed manifold through the use of shut-off valves and the use of each tank’s boost pump to provide positive fuel pressure.

Figure 2-2: Typical HC-130N/P Auxiliary Fuel Panel

Figure 2-3: Typical HC-130N/P Fuel System in Tank-to-Engine Configuration

2.4.1.3 When the crossfeed manifold shutoff valves are opened and fuel is drawn from the external, fuselage, auxiliary, or other main fuel tanks, it is described as crossfeed operation (see Figure 2-4). This is usually used during cruise flight to utilize the fuel contained in the auxiliary, external, and fuselage tanks.

 

Figure 2-4: Typical HC-130N/P Fuel System in Crossfeed Configuration

 

2.4.1.4 The boost pumps for the external, fuselage, and auxiliary tanks have a higher output pressure (28-40 psi.) than the main tank boost pumps (15-24 psi.). This design feature allows the main tank pumps to remain on, so that in the event that fuel is not delivered from any of these tanks, the main tank boost pumps deliver the required fuel immediately. In each case, the higher pressure over-rides the weaker main tank boost pumps. When the selected tank is empty, the main tank pumps assume the task of supplying fuel to the crossfeed manifold. In an emergency, fuel can be dumped overboard by using dump pumps located in each tank and directed through the dump manifold to the dump masts located in each wing tip.

2.4.1.5 A safety improvement implemented by the Air Force has been the transitioning from JP-4 fuel to the less volatile JP-8. Some slight problems have surfaced during this fuel transition, such as small fuel leaks which have been attributed to o-ring shrinkage. The solution has been to replace o-rings with new ones on an "as required" basis. Additionally, improvements in tank sealing technology have drastically reduced the number of external fuel leaks attributed to improper fastener installations or joint sealing interfaces.

2.4.1.6 Over the years, the basic fuel system has been modified and/or enhanced, depending on the mission design series (MDS). Some C-130s have fuselage tanks to extend their range and/or allow other aircraft to be refueled in flight. Additionally, some aircraft have been modified to receive fuel in flight from an aerial tanker.

Fuselage Tanks. The fuselage tanks were added to the aircraft to enhance the fuel capacity/range. Consisting of one or two 1800 gallon cylindrical tank/s they are mounted in the cabin section of the fuselage, near the aircraft’s center of gravity. The fuselage fuel tank has either a single or dual pump configuration. The pumps are rated for 28-40 psi. The single and dual pump tank configuration is not consistent from aircraft to aircraft, since these tanks are removed and replaced for mission purposes and maintenance requirements routinely. Depending upon mission requirements, some planes will fly with zero, one, or two fuselage tanks. The fuselage tanks are plumbed into the aircraft’s refuel/dump manifold. The right external dump valve is controlled with the right external crossfeed valve switch, connecting the dump manifold to the crossfeed manifold. This allows fuel from the fuselage tanks to be routed to the crossfeed manifold for engine consumption. The fuselage fuel tanks vent system is unique to the other aircraft fuel tank vent systems. Because the fuselage tank resides in the aircraft’s pressurized cabin section, the fuselage tanks internal space is maintained at cabin pressure to prevent structural damage to the tanks. This is accomplished by a vent system that allows cabin air to enter the tank when the aircraft is pressurized or fuel is pumped from the tank. The vent system also allows pressure in the tank to be vented outside the aircraft when the aircraft is depressurized or fuel is pumped into the fuselage tank.

2.4.1.7 The C-130 basic fuel system has required no major modifications to resolve safety concerns. However, slight modifications such as the addition of the 1360 gallon external pylon tanks (installed on C-130E/H aircraft and their variants), valve relocations and operations, and plumbing routing, have been incorporated to extend the capabilities of the C-130. The C-130 fuel system experiences normal wear and tear which eventually requires individual components to be repaired/overhauled and/or replaced. For example, boost and dump pumps fail; o-rings and couplings leak; gate, and butterfly valves fail; and fuel system plumbing may become damaged. Occasionally, isolated fuel system related problems have required depot engineering assistance.

2.4.1.8 Failure of the fuel system to provide fuel to the engines centers around two conditions:

Insufficient fuel getting to the engine burner cans - Insufficient fuel could be the result of a fuel leak, inadvertent fuel dumping, fuel system or engine component failure, or allowing the tank to be emptied without other tank boost pumps on or without switching to a fueled tank. Failure to prime the fuel manifolds can result in existing air in the fuel manifolds being sent to the engines. The consequence of these conditions may be an engine flameout.

Contamination - Contamination interferes with the engine fuel system’s ability to deliver a sufficient quantity of fuel to the engine combustion chambers which can reduce the power output of the engine. The circumstances leading to this are contaminated fuel introduced at the last refueling, fuel becoming contaminated due to in-tank debris from maintenance or internal deterioration of the tank or fire suppression foam, or water due to condensation or rain entering through filler caps. In extreme cases, such contamination may clog filters and their associated bypass valves, resulting in engine flameout.

2.4.2 Engine Fuel System

Figure 2-5: C-130 Engine Fuel System

2.4.2.1 The main components of the engine fuel system consists of the fuel pump, fuel control, temperature datum (TD) valve, and fuel nozzles, along with drain valves and two fuel filters. Fuel flow through these components is shown in Figure 2-5.

2.4.2.2 Fuel supplied from the aircraft fuel tanks is delivered to an engine-driven, two-stage, gear type fuel pump. In the event of the failure of one stage of the pump, the two-stage design ensures the engine will be supplied with sufficient fuel.

2.4.2.3 The fuel control is a hydro-mechanical metering device designed to supply a controlled fuel flow to the engine during all operating conditions. Located on the engine, the fuel control measures the RPM of the engine, the inlet air temperature, inlet air pressure, and throttle position. Fuel metered by the control is equal to engine requirements, plus an additional 20%, which is for the use of the TD valve, a part of the TD system. There are six fuel nozzles mounted in the "diffuser case" of each engine. One fuel nozzle extends into the forward end of each of the six combustion liners. Looking like large metal cans with holes punched regularly around their sides to carefully contain the flames, two of these opposing liners have igniter plugs to ignite the fuel during engine start. As the fuel nozzles disperse the fuel in a fine spray to maximize combustion efficiency within the engine, interconnecting tubes between the liners spread the flame and assure complete combustion within.

2.4.2.4 The TD valve is an electrically operated fuel-trimming device. All fuel flowing from the fuel control must pass through it before being sent to the fuel nozzles. Since the TD valve receives 120% of engine fuel flow requirement from the fuel control, some fuel must be bypassed by the valve. Fuel in excess of that required by the engine is bypassed and returned to the inlet of the fuel pump. When only that 20% surplus is bypassed, this is known as a "NULL" condition. When less than 20% is being bypassed to the fuel pump, this is known as a "PUT" condition. When more than 20% is being bypassed, this is known as a "TAKE" condition.

2.4.2.5 A small drive motor operates a piston inside the TD valve which adjusts how much fuel is ultimately passed on to the fuel nozzles. This drive motor is controlled by a signal from the TD amplifier (TD amp).

2.4.2.6 The TD system works to help keep the engine running at the temperature and power setting the pilot selects when he moves the throttles. It also allows the engines to burn several different kinds of fuel. The TD amp receives a temperature signal from 18 engine "thermocouples." These are metal probes which accurately measure high temperatures within the engine. They are mounted at the inlet of the turbine section of each engine, just behind where the fuel is burned and the resultant gases are near their hottest point. The TD amp compares an average of these 18 signals from the inlet of the turbine with the "reference signal" in the TD amp (for start temperature limiting protection), or from the temperature setting commanded by the pilot’s throttle movements. The throttle’s signal is generated through a "potentiometer" (i.e., a rheostat) in the "throttle coordinator," which is also on the side of the engine. The signal from the potentiometer corresponds to the position of the engine throttle lever. When the temperature signal from the thermocouples matches the reference signal, the TD amp sends no signal to the TD valve, and the valve remains in the "NULL" Position. If the temperature signal is greater than the reference signal, the TD amp sends a signal to the TD valve to "TAKE" fuel. If the temperature signal is less than the reference signal, the TD amp sends a "PUT" signal to the TD valve. In this fashion, through thousands of small corrections, the TD system constantly works to keep the engine operating at the desired temperature.

2.4.2.7 Related Deficiencies and Concerns

DEFICIENCY: Some fuselage tanks have only one fuel pump.

ON-GOING RESOLUTION: Continue installing pumps until all fuselage tanks have two pumps.

DEFICIENCY: In the event of a main tank failure, T.O. 1C-130(H)H-1, page 3-23 allows the use of the dump pump from the same main tank to crossfeed to its respective engine. This is an adequate procedure but its use should be discontinued before the dump pump inlet is uncovered. According to T.O. 1C-130(H)-1, page 1-47, this occurs at approximately 1,500 to 2,100 lbs, depending upon the specific type of C-130.

RECOMMENDATION: The BAR recommends that Air Force establish a fuel quantity limit for using the above procedure and revision of all affected C-130 T.O.s accordingly.

2.5 Electrical System

2.5.1 Four engine-driven alternating current (AC) generators and an auxiliary generator power the AC electrical system of the C-130. On aircraft prior to tail number 74-1658, an auxiliary AC generator is driven by an air turbine motor (ATM) which is operated by high-pressure air from either the gas turbine compressor (GTC), or from an operating engine. The GTC cannot be operated in-flight, but the ATM can be operated to supply AC power if the bleed air manifold is pressurized. Newer aircraft received an auxiliary power unit (APU) which can be operated in flight. The APU generator is directly splined to the APU and does not rely on bleed air to operate.

Figure 2-6: C-130 AC Bus Power Sources

2.5.2 The AC generators are connected through transfer contactors (relays) to four AC buses: the left hand AC bus, the essential AC bus, the main AC bus, and the right hand AC bus. The transfer system is automatic and operates in such a manner that any combination of two or more engine-driven AC generators will power all four AC buses. With only one AC generator supplying power, only the essential and main AC buses will be powered. In the event of complete loss of all AC generators, none of the AC buses will be powered. Operation of the APU or ATM generator will supply power only to the essential AC bus. Combinations of operating generators and the buses they power are shown on the AC bus power sources chart in Figure 2-6 above.

2.5.3 The normal source of direct current (DC) power is four transformer-rectifier (TR) units. These units change the three-phase AC power from the AC generators to 28 volt DC power. A 24-volt battery is provided as an emergency source of DC power. Two of the TR units are connected to the essential AC bus with their output supplying power to the essential DC bus. The other two TR units are connected to the main AC bus with their output supplying the main DC bus. In the event of total AC power failure, the essential DC and main DC buses will also lose power. In this case the only remaining power source is the aircraft battery which will power the battery bus and the isolated DC bus to provide basic instruments and communication for the flight crew.

2.5.4 Related Deficiencies and Concerns

DEFICIENCY: Configuration Control - Over the previous 10 years, detailed control over and knowledge of the exact configuration of each aircraft has been lost. This is the result of having many different C-130 users, several diverse missions, and no cohesive program to force compliance upon the various operators. As a result, these aircraft were modified in a less than stringently controlled environment, and by modification teams which did not always precisely follow the modification drawings. Changed under provisions which allowed the C-130 manufacturer to deliver new aircraft with prior modifications installed, their users sometimes preferred cockpit equipment arrangements different from the standard C-130 configuration, but did not fully document these changes. In addition, there are users who modified the aircraft to meet mission needs without documenting the changes, as well as test agencies who did not document their modifications.

ON-GOING RESOLUTION: The BAR supports the C-130 Systems Program Office efforts to institute a configuration management program for USAF C-130 users. Through various directives, the users are required to document all changes and process those changes through a configuration-control process that includes air-worthiness and major command concurrence. Additionally, a digital photographic record and digital location matrix for each aircraft are being gathered. These data are the core of the continued documentation of aircraft configuration as aircraft modernization progresses. Currently, C-130s are undergoing modification to upgrade the electrical system to provide clean avionics power, install defensive avionics, replace unsupportable auto-pilots and install a global positioning system (GPS). These modifications are prerequisites for future upgrade efforts, which will include the recorders, the second INU, the radar, a modernized avionics suite and flight station. Future plans include replacement of the flight data and cockpit voice recorders, replacement of the radar, and installation of a second inertial navigation unit (INU) to replace vertical gyros and compasses.

DEFICIENCY: Many aircraft have wiring that is reaching the end of its service life. Additionally, avionics wiring has been damaged during numerous modifications which install or relocate systems. This wiring degradation increases its susceptibility to EMI. Also, the structure of these aging aircraft has lost some electrical bonding properties which are essential to avionics operation. The C-130 uses the aircraft structure as ground return for the electrical equipment. Installation of the structural components must be accomplished to ensure that each structural piece is electrically the same (zero volts). Electrical systems behave erratically when the ground potential is not zero volts.

RECOMMENDATION: The modifications mentioned above serve to replace most of the electronic wiring and allow the remaining wires to be inspected and repaired or replaced. The immediate need for correcting wiring short-comings, relative to some rollback scenarios, is for the replacement of synchrophaser interface wiring bundles. Also, the aircraft can be improved by rewiring wings and wheel wells. Many maintenance procedures address bonding/grounding integrity; however, both will be assessed and improved during the modernization effort. A continuing problem is the susceptibility of the aging synchrophaser interface wiring bundles to EMI. The BAR recommends the C-130 System Program Office propose a modification to replace the synchrophaser interface wiring bundles on all C-130 aircraft.

DEFICIENCY: Digital Flight Data Recorder (DFDR) - The current DFDR is an unreliable circa-1970s magnetic tape system which has limited channels for recording data. Data recording captures only 25 hours of data. Verification that the system is functional is an arduous two-month process involving shipment of verification tapes to a remote reading site. This system and the accompanying cockpit voice recorder (CVR) are inconsistent with the needs of the safety boards and are incompatible with the projected configuration of the modernized instrument system.

ON-GOING RESOLUTION: The BAR supports the C-130 SPO efforts to modernize the DFDR/CVR in two phases. First, the current DFDR will be replaced with a form, fit, and function solid state recorder which will have additional parameters added. This system will use a solid state recording media which can be read by the using unit to verify proper function. Second, as a part of the modernization of the aircraft, a large parameter capacity system will be installed to accomplish data and voice recording. This system will be compatible with data buses to allow parameters to be recorded directly.

DEFICIENCY: The loss of the DFDR and Cockpit Voice Recorder (CVR) when the power is lost from the last engine generator is considered a deficiency because there is no available record of crew actions or aircraft performance from that point until ground or water impact.

RECOMMENDATION: This report supports C-130 SPO efforts to develop and implement a modification which would provide power to the DFDR and CVR during battery only operation.

DEFICIENCY: The exact desired parameters for DFDR recording need to be defined so as to ensure the DFDR records the essential performance data necessary for post-mishap analysis, considering FAA and NTSB guidelines and/or recommendations.

ON-GOING RESOLUTION: This report supports Air Force Safety Center efforts to provide a list of these parameters.

DEFICIENCY: Review of the aircraft configuration revealed that the ESU modification has configured the generator controls such that, on some E-model aircraft, the crew must shut down the engine when its generator has failed.

RECOMMENDATION: The BAR recommends the C-130 SPO develop and implement a modification which would install generator disconnects or bearing failure lights in all ESU aircraft.

DEFICIENCY: The crew cannot operate the fuel valves, nor can the engine igniters be powered when the aircraft is in an airborne, battery-only condition.

ON-GOING RESOLUTION: The BAR supports development and implementation of a C-130 modification which would bypass the touch-down relay to allow the DC isolated bus to power the DC essential bus, thus allowing fuel valves and igniters to function. This effort would be accomplished concurrently with the existing modification to add an additional reverse current relay. This will provide the ignition source to restart the engines if fuel is available. The BAR does not consider the APU replacement a safety issue since the above provides an alternative way to provide restart capability to an aircraft with windmilling engines. This proposal is currently being evaluated by WR-ALC and is awaiting funding. If funded, it should be complete by Dec 31, 1998. The BAR reviewed the restart capability of the C-130. This is identified as a deficiency elsewhere in this report. Those C-130 aircraft manufactured before 1974 utilized a GTC and ATM to provide limited aircraft electrical power on the ground and in certain in-flight emergencies. The ATM uses bleed air from either the GTC (ground use only) or engines to produce electricity. In the air, the GTC can not be operated so only bleed air from engines can be used to power the ATM. This design feature means that with no engines operating, the ATM can not provide any electrical power. The post-74 aircraft had an APU added to provide electrical power in the same situations as the ATM. It has the additional capability of utilizing external air flow and can provide electrical power with no engines running. The Air Force has considered a retrofit to replace the GTC/ATMs on pre-74 aircraft, with an APU. The decision process involved a risk assessment and cost considerations. The high reliability of the C-130, the absence of any four engine flame-outs in over 24 million flight hours, and the high cost ($1,200,000 per aircraft) argued against the modification. The Air Force is currently proposing a broad ranging upgrade to the C-130 that includes the APU. This modification is driven by international airways conventions, required avionics upgrades, configuration control, and maintainability issues. Including the APU in the modification program substantially reduces the cost of doing the APU upgrade independently.

2.6 Pneumatic System

2.6.1 The pneumatic system provides compressed hot air "bled" from the engine compressors to operate a number of aircraft systems, such as engine ground starting, anti-icing, air conditioning and heating, and pressurization. This air is distributed to various locations within the aircraft via metallic ducts. Over time, these ducts have exhibited a susceptibility to corrosion, resulting in a rupture of the ducting. Because of the heat associated with a bleed air leak, significant damage to the aircraft and other systems can result from a duct failure. As a result of several previously documented duct failures, a program is currently in progress to replace these bleed air ducts with ones made from a more corrosion-resistant nickel alloy. At this time, all of the flight-safety critical ducts have been replaced in all C-130 aircraft, and many other less critical ducts have been or are scheduled to be replaced by the C-130 SPO.

2.6.2 During the review of C-130 flight safety, the BAR noted no flight safety concerns related to the aircraft’s pneumatic system that had not been addressed.

2.6.3 Related Deficiencies and Concerns

DEFICIENCY: None.

2.7 Hydraulics System/Flight Controls

2.7.1 The C-130 has three separate 3,000 psi hydraulic systems: the booster, utility and auxiliary systems. These systems are used to operate flight controls, cargo ramp and door, flaps, brakes, nosewheel steering, and the landing gear. The booster and utility systems are supplied by four engine-driven pumps mounted on each engine’s reduction gearbox. The auxiliary hydraulic system is supplied by an electrically driven pump. For reasons of safety and system reliability, the flight control boost packs for the elevator, rudder, and ailerons are usually pressurized by both the booster and utility systems. Manual operation of the flight controls without any hydraulic assistance is also possible during an emergency.

2.7.2 During the review of C-130 flight safety, the BAR noted no flight safety concerns related to the aircraft’s hydraulic system that had not been addressed by the C-130 SPO.

2.7.3 Related Deficiencies and Concerns

DEFICIENCY: None.

Section 3.0

Operations and Training

3.1 C-130 Technical Manuals ("Technical Orders")

3.1.1 Technical Orders apply to both operators (primarily flight manuals) and maintenance personnel. The BAR will address the flight manual deficiencies in this section. For the aircrew, the flight manual describes the aircraft and how to operate it. It is divided into several sections, including normal operations and emergency procedures. There is a second volume called the performance manual that contains detailed charts to calculate aircraft performance for given conditions (e.g., takeoff , climb, cruise, descent, and landing). The aircrews need an accurate, easily read document for use in flight during normal, abnormal and emergency situations. The following problems were identified with the current manuals.

3.1.2 One flight manual had over 30 active operational supplements altering the basic document and requiring changes to be annotated by hand.

3.1.3 One operational supplement required over 12 hours to post, including write-in changes to critical portions of the emergency section of the manual .

3.1.4 Some charts in the performance manual contain inaccurate data. For example, torque charts in the C-130H model performance manual are known to be in error by up to 7%. In other cases, aircraft configuration changes have outpaced performance manual updates, creating problems in many aircraft variants. One example of this resultant mismatch is the drag index for the Commando Solo II aircraft. Finally, important charts are not available. For example, three- and four-engine climb gradient charts are needed for all models of the C-130.

3.1.5 Several variants of the aircraft have their own separate flight manual. This is necessary because of unique aircraft differences. However, many identical systems in these multiple variants have different procedures mandated in their flight manuals. For example, some commands require engine run-ups while some don’t; some require top of the aircraft inspection and some don’t, some require a positive fuel flow check while some do not. There are individual units where flight manuals for the various aircraft don’t match. In a special operations unit, with a mixture of specialized and basic C-130s, two separate commands manage their two flight manuals. Crews are expected to be competent in both, but even the basic operating procedures are not the same.

3.1.6 All USAF C-130s do not use AF flight manuals. Some special mission aircraft use Lockheed Technical Manuals (LTMs) for flight operations. Crewmembers assigned to these units also operate basic C-130s which use AF flight manuals. As in the above example, because the LTMs and the AF flight manuals do not always contain the same procedures or guidance, aircrew must use different procedures for identical systems depending upon which type aircraft they are flying.

3.1.7 These major operating procedure differences are a by-product of several commands having responsibilities for the flight manual content for the variants under their control. A single lead agency, responsible for conformity, would reduce this problem significantly.

3.1.8 Related Deficiencies and Concerns

DEFICIENCY: Technical Orders currently contain too many supplements that are too large and laborious to incorporate.

RECOMMENDATION: The BAR recommends that the Air Force update, consolidate and standardize technical orders, flight manuals, and published guidance, and to limit the number of write-in changes that can be introduced before a manual must be replaced.

DEFICIENCY: Non-standardized procedures among the many versions of the flight manuals.

ON-GOING RESOLUTION: The C-130 Program Office will host a meeting, tentatively scheduled for 2-13 February 1998, with all C-130 major commands to identify the non-standardized procedures and reach agreement on standard procedures.

DEFICIENCY: Performance manual charts do not match aircraft performance, nor contain needed information.

ON-GOING RESOLUTION: The C-130 Program Office plans to correct the performance manuals and will get this effort underway in the third quarter of fiscal year 1998.

3.2 Aircrew Life Support Equipment

3.2.1 The BAR reviewed the guidance directing the placement of life support equipment carried on C-130 aircraft. They found different commands had different requirements. When the CONUS CAD C-130s moved from ACC to AMC there were significant guidance changes. Currently AFI 11-302 Vol. 1 is in coordination and will provide Air Force-wide guidance standardizing required C-130 life support equipment. The BAR is comfortable that the draft AFI 11-302 addresses the significant issues and will provide adequate guidance and standardization. It is due out in early 1998.

3.3 Ditching/Bailout

3.3.1 A review of ditching/bailout information and procedures in various flight manuals reveals a significant variation in implied survivability of a ditching maneuver. Flight Manuals managed by AMC and Air Force Special Operations Command (AFSOC) have significantly different guidance. Specifically, T.O. 1C-130H-1 managed by AMC states:

"…ditching of transport-type airplanes can usually be accomplished with a high degree of success." Pg. 3-71 under "ditching."

3.3.2 However T.O.-1C-130(A)U-1, managed by AFSOC, states

"…ditching of the AC-130U can be accomplished with a low probability of aft crew member survivability. The flight deck may be survivable, but ditching should be considered an absolute last resort for any crewmember." Pg. 3-90 under "ditching."

3.3.3 Another apparent contradiction appears in T.O. 1C-130H-1 pg. 3-71 under "ditching characteristics"

"…Reasonably high probability that the airplane can be landed on water without major collapse of structure or a sudden rush of water into occupied compartments."

3.3.4 Compare this citation to the following language found in T.O. 1C-130(A)U-1 pg. 3-90 under "ditching characteristics"

"…reasonably high probability the aircraft structure will collapse followed by a sudden rush of water into occupied compartments."

3.3.5 These two flight manuals addressing the same subject portray vastly different projections of success for a ditching attempt. Of similar concern the diagram on page 3-76 of T.O. 1C-130(H)H-1 titled "Emergency Exits-Water" depicts a fully intact C-130 floating in the water. None of the aircraft in the three most recent C-130 ditchings survived intact. The referenced diagram gives support to the idea of a survivable ditching.

3.4 C-130 Aircrew Training

3.4.1 Categories of Training C-130 Aircrew Training falls into four major categories: Initial C-130 Qualification Training, Initial C-130 Mission Qualification Training, Continuation Flying Training, and Continuation Ground Training.

3.4.1.1 Initial C-130 Qualification Training. This is the first formal Air Force training course a prospective C-130 crew member will attend and is normally conducted at Little Rock Air Force Base in Arkansas. It consists of classroom, aircraft simulator, and flight training. The classroom phase covers the basics of aircraft systems and checklist procedures. During the simulator phase, the new pilots and engineers learn to integrate their systems knowledge and checklist use into a coordinated crew effort. They practice both normal and emergency procedures, simulate flying entire missions, and develop an understanding of crew coordination, learning to work together effectively in a crew environment. The two combined phases consist of 210 hours in the classroom, and 36 hours in the simulator. Navigators receive training in the aircraft systems navigation simulator to become familiar with how to guide the aircraft using its self contained navigation system (SCNS), and the other compass and navigational aids on board. During the flight phase, the new crewmembers will practice basic aircraft maneuvers, both on the ground (i.e., engine start, taxiing, and backing), and in the air (e.g., takeoffs and landings, en route navigation, instrument approaches, and visual traffic patterns). Flight hours logged vary by position, with new pilots accumulating the most hours (approximately 60 hours per pilot) during these courses owing to the necessity to develop their flying skills. The successful completion of this training qualifies an individual to fly "basic air-land missions," i.e., those requiring getting from one point to another while carrying passengers and/or cargo, in the C-130. Little Rock Air Force Base historically produces approximately 2,400 graduates (cumulative, all crew positions) per year.

3.4.1.2. Initial C-130 Mission Qualification Training. This training initially qualifies crewmembers in a specific operational mission of the C-130 (such as airdrop, short field landings, rescue, special operations, firefighting, electronic combat, psychological operations (PSYOP), and others. Like initial qualification, this phase also consists of classroom, simulator, and flight training. For those trained in the combat delivery mission, which comprises the largest portion of the C-130 crew force, initial airdrop and short field landing formal training (also known as "assault landing" training) is normally conducted at Little Rock Air Force Base, but class availability sometimes necessitates in-unit training at home station. Most C-130 special mission qualification training is conducted in-unit or at Kirtland Air Force Base (for special operations units and rescue).

3.4.1.3 Continuation Flying Training. Once crewmembers complete initial qualification and mission qualification, they must maintain that qualification by successfully completing certain training events on a recurring monthly, quarterly, or semi-annual basis. Referred to as "maintaining currency," accomplishing these training events assures that the individual refreshes skills and familiarity with essential maneuvers, therefore staying qualified to fly the aircraft. This training is conducted in-unit.

3.4.1.4 Continuation Ground Training. Staying qualified to fly requires completion of other recurring monthly, quarterly, semi-annual, or annual ground training events. These events cover a broad spectrum of flying-related activities to include physiological training, annual flight simulator refresher training (in normal and emergency procedures), life support training, and cockpit resource management training (CRM). CRM training focuses on enhancing crew synergy, coordinating on mission accomplishment and handling unusual emergency situations. Continuation classroom and simulator training is usually more advanced and tailored to the experience of the crew. This training is usually conducted at home station, or at a remote satellite simulator location. The focus of this training is on more in-depth systems knowledge and handling of more complex emergency procedures. This simulator refresher training normally lasts three days with four hours of academics and four hours in the simulator each day.

3.4.1.5 Initial Water Survival Training. Currently course number SV-90-A, Non-parachuting Water Survival, is the required course for large aircraft (non-ejection seat) crewmembers. The course focuses on ditching procedures to the exclusion of bailout. The BAR is concerned about two issues. First, it leaves the crew deficient in techniques of over-water bailout. Second, it encourages the belief that ditching is the preferred option. AMC/DOT is working an initiative to restore overwater bailout to the curriculum of SV-90-A.

3.4.2 Contractor Aircrew Training System The Little Rock Air Force Base C-130 classroom and simulator training (both formal school and continuation training) are normally conducted by a civilian contractor (Hughes). Their instructor corps consists mostly of retired military C-130 crewmembers with many years of C-130 flying experience. Additionally, the aircrew training system (ATS) contract requires the syllabus and instructors to be responsive to the latest changes and safety issues in the C-130. Specifically, the contractor is required to include information from safety supplements in their classroom training within 48 hours of safety supplement release. The contractor will also update the simulator scenarios to include these safety issues. The intent is to expeditiously raise crew awareness and train the force on the latest operational and safety issues affecting the C-130.

3.4.3 Comments on Continuation Training Overall, the team found C-130 initial and continuation training to be a thorough, effective and responsive process. When a new safety issue is addressed in a safety supplement, incorporating it into the simulator refresher classroom training within 48 hours, and ultimately incorporating it into training scenarios, is an effective training tool. However, the BAR found several issues that warrant comment, and which may have possible impact on C-130 training and operations:

3.4.3.1 Wide Variety of C-130 Missions and Models. Formal school training is conducted on C-130E models. While these E-models have served as a good training platform for many years, modifications (EC, HC, WC, etc.) and modernization (H-1, H-2, and H-3 aircraft) necessitate that many students undergo differences training in their particular aircraft upon arrival at home station. The burden of teaching the operation of C-130 aircraft other than E-models has been delegated to the individual unit. The number of units and personnel needing differences training grows with each new modification and modernization to the C-130. This philosophy is not consistent with an integrated training program that strives for economy of instruction and assurance of effective, standardized instruction. The team is concerned that procedures and techniques taught in-unit may not be standardized, nor receive the degree of review and scrutiny normally associated with "formal" C-130 training.

3.4.3.2 Formal School Challenges. In the past few years, the formal school at Little Rock has had difficulty keeping up with the rising training demands (i.e., the number of students to be trained). This increase in training demand has been due to a number of factors, to include: increased crew ratios for pilots and loadmasters, the "banked pilot" program (pilots trained through Undergraduate Pilot Training but delayed in being assigned to an operational aircraft due to previous surpluses in the pilot force), increased numbers of first assignment instructor pilots (or "FAIPs") assigned to C-130s, and a shortage of available C-130 instructor pilots. The result is a heavily worked training system where most training is accomplished at Little Rock. However, some students’ assignments are delayed while they await training, or they must accomplish the training at home station with in-unit waivers. The goal should remain to train all initial qualification training students at the formal school to promote standardization in operating the C-130 worldwide.

3.4.3.3 Training Video. The team viewed a training video that was developed following a Colombian Air Force ditching of a C-130. The BAR was in general agreement that this video was an effective training tool. An updated training video would incorporate the lessons learned from King 56, the Colombian ditching, the gunship mishap in Africa, and other ditching events, and would be a valuable training tool.

3.4.3.4 Ditching vs. Bailout Training. The BAR reviewed flight manual guidance for ditching and bailout. T.O. 1C-130H-1 pg. 3-64, in "Bailout Over-water" states:

"Consideration of various unfavorable factors involved in an overwater bailout limits the decision recommending overwater bailout to several specific instances: namely, when visual contact is made with land, or adequate surface help; when wind and sea conditions are such as to preclude ditching; when fire or loss of control makes ditching impossible."

3.4.3.5 This discussion clearly favors ditching over bailout in over-water situations. The BAR believes this priority needs to be reviewed and revalidated in light of available ditching information and anticipated life support / survival equipment availability. The BAR further found that there is currently no requirement to review ditching or bailout drills.

3.4.3.6 In our visits with crew members around the country, the BAR found them to be familiar with ditching procedures outlined in their respective dash ones. The overwhelming majority were familiar with the general details of the Colombian aircraft ditching. There was an awareness among the crews that ditching, even under the best of circumstances, carried the probability of extensive damage to, and immediate flooding of, the aircraft shortly after initial impact. They acknowledged a strong tendency to want to stay with the aircraft, rather than bailout and be strung out across the water--away from the majority of the available survival gear stowed aboard the airplane. The BAR believes the flight manuals should be updated for the best information available on ditching and how to prepare for and successfully execute the maneuver. An expanded discussion of the merits of ditching versus bailout in the dash one would be helpful as well. Clearly, the crews understand ditching to be an emergency procedure--the probability of success is directly proportional to conditions at the time of ditching: daylight, calm sea state, lightweight, powered flight, & favorable wind direction. Under any other conditions, the probability of success becomes marginal at best.

3.4.3.7 Related Deficiencies and Concerns

DEFICIENCY: Periodic review of ditching and bailout procedures by aircrews is not currently required.

RECOMMENDATION: The BAR recommends that the Air Force establish a requirement for all crews to review ditching and bailout procedures on the first leg of overwater missions.

DEFICIENCY: Ditching information in flight manuals is inconsistent and inaccurate.

RECOMMENDATION: The BAR recommends that Air Force work to standardize this information between models of the same aircraft and reverify the accuracy of the information contained in the flight manuals on bailout and ditching, including the advisability of each, considerations involved in the decision, and the probability of survival in each case.

DEFICIENCY: Bailout over water information in the flight manuals needs to be reviewed. By favoring ditching over bailout, flight manuals are endorsing a recognized procedure with a low probability of survival. While this may be appropriate, the BAR believes a review is warranted to include proposed survival equipment changes. Clearly, with passengers on board (depending upon their number, ages, experience, sea state, and availability of parachutes and life support equipment), ditching may well be the only option.

RECOMMENDATION: The BAR recommends that Air Force work to standardize this information between models of the same aircraft and reverify the accuracy of the information contained in the flight manuals on bailout and ditching, including the advisability of each, considerations involved in the decision, and the probability of survival in each case.

3.4.3.8 Systems Training. The BAR discovered an inaccurate belief within the crew force that the synchrophaser is responsible for most, if not all, power anomalies in this aircraft. This "synchrophaser psychosis" results in both the crew force and maintainers being spring loaded to blaming synchrophasers when other systems such as aircraft fuel, electrical, or bleed air might be involved. The BAR identified several incidents where focusing on the synchrophaser delayed identifying fuel problems.

3.4.3.8.1 A critical action "bold face" procedure was developed to address the serious situation of multiple engine power loss/RPM rollback emergencies. Results of BAR initiated flight tests have confirmed the inability of the engines to sustain combustion due to fuel starvation in certain situations. These situations can result in power losses that can be recovered by turning on the main fuel tank boost pumps and closing the crossfeed valves. If no corrective action is taken all four engines may flameout.

3.4.3.8.2 The flight manual has contained a four-engine rollback procedure for a number of years. While not a bold face item, most, if not all units, expected crew members to commit this procedure to memory, just as they would a bold face procedure.

3.4.3.8.3 This newly issued Multiple Engine Power Loss/RPM Rollback procedure has four steps that are "bold face" (critical actions which must be committed to memory). The first two addresses fuel and ensures the fuel pumps are on and the fuel system is in "tank to engine" configuration. The third directs placing all propeller governor control switches to "mechanical governing" This should remove all electrical inputs from the synchrophaser to the propeller control assembly. The final "bold face" step directs placing all temperature datum control switches to "null". This removes any electrical corrections from the TD system and returns the TD valve to a 20% bypass position. The first four steps of the procedure will allow the crew to recover from either a possible fuel starvation situation or electrically induced synchrophaser or TD system malfunction. Once the situation is stabilized, and the aircraft is in its most basic operational mode, the crew will have time to analyze the specific situation/malfunction.

3.4.3.8.4 The implications of the flight test results impact several procedures in the flight manual. For example, before the generators are turned off in the case of an electrical fire, the flight manual should be updated to address closing the crossfeed valves. This is only one example of impacts on the flight manual.

3.4.3.9 Cockpit Resource Management: Cockpit Resource Management has been an element of aircrew training for several years. Despite this training both in the class room and in the simulator, there continues to be mishaps where CRM is clearly a significant factor. Currently, annual ground training is focused on improving crew synergy and coordination to enhance safe, efficient mission accomplishment in handling aircraft emergencies. The classroom portion of the training addresses human interaction, communications and group dynamics. Simulator training includes only those crew members who have positions in the simulators and is not done by all commands. The concept is to apply classroom lessons in scenarios in the cockpit. CRM training is conceptually good and professionally presented; however, anecdotal evidence suggests that the lessons are not fully incorporated into crew behavior. It is clear to the BAR that the CRM program needs to be reviewed. If the data is available, review a random subset of pre and post CRM training mishaps. Has the training improved the mishap rate? Is CRM properly focused, or could modifications to the program improve the crews performance without adding to the training burden

3.4.3.10 Multiple Aircraft Configuration: There is considerable discussion within this document concerning various aspects of configuration control. This issue has operational impacts. During their unit visits, the BAR found that several units had more than one configuration of the same series of aircraft. This creates situations in which instrument locations, procedures and systems details are different.

3.4.3.11 Techniques vs. Procedures: A core principle in flying, both commercial and military, is the strict adherence to established procedures. It appears that small, isolated flying communities have the potential to develop, intentionally or accidentally, techniques masquerading as procedures that have not been evaluated and approved by appropriate authority. One specific example, discussed in detail elsewhere, is the technique of turning off the main tank fuel boost pumps when feeding all four engines from the fuselage tank. The BAR discussed at length mechanisms to re-establish the sanctity of the flight manual, but that requires the repair of the flight manual system and the unification of the flight manuals under a single manager.

3.4.3.12 Aircrew Experience Level: Each command designates their standards for aircrew experience. The BAR reviewed crew force experience levels and found most operating commands met or exceeded those standards. Overseas, Special Operations, and both Guard and Reserve units generally exceeded experience objectives by a large margin. These commands also exceeded the experience levels generally found in active duty CONUS combat aerial delivery units. While important to monitor, the current crew force has a realistic capability to meet current taskings safely.

3.4.3.13 Related Deficiencies and Concerns

DEFICIENCY: The BAR directed flight test identified flight manual discrepancies with respect to the fuel management in certain situations.

RECOMMENDATION: The flight manual should be reviewed to incorporate the lessons of the flight tests in relevant areas of the flight manual.

Section 4.0

Maintenance

4.1 C-130 Maintenance Training

4.1.1 The BAR sought to determine whether maintenance personnel receive adequate training to enable them to safely maintain C-130 aircraft. They examined the safety aspects of the issue by: visiting sixteen different C-130 units, interviewing maintenance and operations personnel and soliciting their views on maintenance training issues, reviewing incident reports looking for trends, listening to inputs from a toll-free hot line, and talking to depot technicians to get their views on the condition of hardware returned to the depot for repair. As a result of our investigations, two areas were selected for special consideration:

4.1.2 On-the-Job Training (OJT): Since assuming lead command responsibilities for C-130s, Air Mobility Command has continued to monitor and improve training programs. C-130 maintenance training had previously adopted a structured training program, called OJT. This approach enables highly skilled craftsmen and supervisory-level Air Force maintainers, or their civilian counterparts, to train and certify new Air Force personnel in the hundreds of maintenance actions required to maintain Air Force aircraft. As a result of this one-on-one approach, entering technicians learned their skills under the watchful eyes of experienced veterans in their respective fields. The Maintenance Qualification Training Program (MQTP) standardizes OJT for each type aircraft throughout the command. The priority for implementing the MQTP concept was to first optimize the program on the C-141, C-5, KC-135 and C-17, before tackling the more difficult C-130 with its multiple mission design series (MDS) and configurations. This program has been successful and the C-130 MQTP classes will begin in March 1998.

4.1.3 Training Program Improvements: AMC has also continued efforts to upgrade training center mock-ups and trainers, and to develop computer based training (CBT). The BAR found several areas that were noteworthy and other areas where the command was working to improve maintenance training.

4.1.4 Summary: Inputs were received from AMC, ACC, AFSOC, AFRC, and the ANG. The team did not find any maintenance training issues which have flight safety implications.

4.2 Maintenance Experience Levels

4.2.1 The BAR reviewed maintenance personnel experience levels in all of the operating commands. As expected because of their generally longer periods of service, individuals in the Guard and Reserve units generally exceeded the experience objectives, and exceeded the experience levels found in the active duty units. Although there has been a decrease in experience levels as the forces have been downsized, the team found no evidence that the decreased experience level is having an adverse affect on flight safety.

4.3 C-130 Maintenance Inspections

4.3.1 All Air Force aircraft are inspected before flight. For the C-130, aircraft inspections range in detail from the most common flightline inspections performed by aircrews immediately before flight, through all the maintenance inspections to ready the aircraft for the aircrew, all the way to a full programmed depot maintenance, or "PDM" inspection at the depot. Basic preflight and postflight inspections, home station checks, and the isochronal (calendar-based) inspection processes are usually done at the aircraft’s home base of assignment and are performed by the Air Force maintenance personnel assigned to that unit. The PDM inspection process goes on at the larger depot facilities which are set up to handle the major maintenance associated with this level of inspection effort. Each inspection is designed to look at only certain items, which cuts down on duplication of effort between inspections. Items inspected during a home station check may not be looked at during the Isochronal inspections (called "ISO" for short) or might be inspected to a different level.

4.3.2 All of these inspection efforts are directed and governed by USAF technical orders, or T.O.s, which will be explained in Section 4.6. The total number of inspection tasks that are performed on each aircraft in the fleet on a periodic basis is very large, consuming a large amount of man-hours, in order to provide aircrews with aircraft that are safe to fly. It is common practice for some minor inspections to become overdue and completed at the next scheduled maintenance event. This is authorized to allow flexibility in managing the flying schedule plus increasing aircraft availability. The BAR did not find any safety deficiencies or problems with the C-130 inspection process.

4.4 Depot Level Maintenance Impact On Flight Safety

4.4.1 The team posed the following questions: 1. Are there any flight safety concerns about depot level maintenance activities? 2. Are aircraft PDM and individual item depot overhaul activities producing aircraft and equipment that are safe to operate and maintain? The team answered these questions on PDM by looking directly at the C-130 fleet’s PDM, and its propeller system component overhaul processes, materials, and workmanship, to identify any safety concerns or problems which might make the airplane less safe to fly. They went directly to the depot facilities at Warner Robins Air Logistics Center in Robins, Georgia (WR-ALC) where the airplanes undergo major repair and their records are kept. The BAR looked especially hard at the C-130 aircraft fuel system, engine, and propeller systems. They found no significant safety issues with either aircraft or repaired parts coming out of depot level maintenance.

4.4.2 Aircraft PDM visits are based on calendar months since the last visit. C-130 aircraft are scheduled for PDMs at specific intervals, depending on their mission. During each visit to a PDM facility, the depot workers perform certain specific inspections, repairs, or refurbishment operations in accordance with a detailed PDM work package. The depot work package of repairs and inspections is agreed upon with the operational commands (e.g., Air Mobility Command, Air Force Reserve Command, and others) during the Maintenance Requirements Review Board (MRRB) meeting held annually.

4.4.3 The depot also performs any "over and above repairs" (more than what was called for in the agreement) on specific tail numbers as requested by the operational unit owning the aircraft. This might range from paint touchup work to prevent corrosion to repairs carried over as important but not critical enough to prevent safe flight. Depot-level tasks are those "heavy maintenance" tasks that call for more expertise, tools, and special heavy equipment than local flying units normally have. In addition, PDM involves inspections generated under the aircraft structural integrity program (ASIP). The ASIP is an extremely rigorous process, usually involving the original aircraft manufacturer, to ensure that the model of aircraft in question does not suffer a catastrophic structural failure. This is accomplished by performing specific structural inspections, repairs, and replacements developed by engineering analysis, individual aircraft usage monitoring, and in some cases, data obtained by full-scale fatigue testing (i.e., bending and vibrating a part over and over to simulate thousands of hours of operational service to see what happens in the laboratory instead of in flight.) This arrangement is beneficial because the equipment for large-scale repairs and fatigue testing is costly and does not need to exist at every location.

4.4.4 From the safety perspective, the key questions relating to the PDM process are: 1. Are the right inspections and repairs being accomplished, i.e., is the MRRB process correctly identifying the work that needs to be done, and 2. Is the agreed upon work being performed correctly during PDM? The Air Force’s experience with this process over the last several decades has proven the MRRB process to be effective in ensuring that the necessary safety-related depot level maintenance is identified and being performed.

4.4.5 The primary measures of success for PDM quality from the safety perspective is the number and significance of deficiencies reported by operational units upon receipt of the aircraft after its PDM visit. Team members reviewed the past two years of this data and found no safety-related problems. Although field units have expressed some concern from time to time over such issues as the quality of paint application on PDM aircraft and various minor workmanship defects, the overall quality levels are satisfactory. Reported defects were corrected or resolved to the satisfaction of the operational units flying the airplanes.

4.4.6 Component Overhaul. The Air Force has overhauled aircraft parts for many years. C-130 parts are overhauled under the Management of Items Subject to Repair, or MISTR, program. MISTR overhauls items "on-condition," i.e. when the item no longer performs satisfactorily.

4.4.7 The team visited the propeller and the synchrophaser overhaul facilities, interviewed workers, and reviewed production quality records. The BAR looked at the results of investigations into quality deficiencies as well. A review of records reveal that over 90% of all synchrophasers returned for repair had no deficiencies. A sample review of 48 synchrophasers returned for repair revealed no "repeat" offenders. The BAR found no safety related deficiencies and judged these overhaul processes to be sound and effective in producing safe, quality items. The BAR did find that five aircraft tail numbers had repeat synchrophaser problems. When these synchrophasers were tested, there was nothing wrong with them. This points to other systems on the aircraft adversely affecting the synchrophaser.

4.4.8 Related Deficiencies and Concerns

DEFICIENCY: The depot was previously unable to properly track propulsion system components.

ON-GOING RESOLUTION: The depot at Warner-Robins has initiated a serially numbered tracking program to obtain the necessary data in an effort to explain what other aircraft systems affect the synchrophaser.

4.5 Maintenance Practices

4.5.1 The BAR found concerned, qualified personnel who found and fixed the problems reported by the flight crews, or who discovered and fixed problems themselves during routine inspections. However, the team saw two instances that are cause for concern. First, virtually no one in the field appeared to be sampling the fuel in aircraft fuel tanks (referred to as "pogoing" the tank, based on the use of a long hollow pole ["pogo stick"] with a collector jar at the end for visual inspection of the fuel sample). Uniform use of this procedure would more readily identify the presence of water and other impurities in aircraft fuel tanks. Second, a core principle of aircraft maintenance is being overlooked in some cases. The BAR found that some maintainers were not consistent in their use of technical order trouble-shooting procedures and the associated required follow-through maintenance actions. In particular, the team noticed the same "synchrophaser psychosis" previously mentioned had a tendency to cause maintainers to immediately assume the synchrophaser was at fault, rather than to thoroughly test it using the appropriate test equipment and procedures. There were also indications that many maintainers were unfamiliar with how to properly test the synchrophaser. This may well contribute to the trend, noted in Section 4.4 of this report, of 90% of synchrophasers sent to depot for repair showing no need for such repair.

4.5.2 Related Deficiencies and Concerns

DEFICIENCY: Maintainers are not sampling aircraft fuel as required by the T.O.

RECOMMENDATION: The BAR recommends renewed Air Force-wide emphasis on fuel sampling as part of standard maintenance operations to help identify the presence of water or other contaminants in the fuel.

DEFICIENCY: Maintainers are not always properly trouble-shooting reported synchrophaser malfunctions and may not be thoroughly familiar with the procedures required for testing the synchrophaser.

RECOMMENDATION: The BAR recommends renewed Air Force-wide emphasis on proper testing of the C-130 synchrophaser following reported malfunctions, and on more thorough training for maintenance personnel in the performance of those tests.

4.6 Technical Orders

4.6.1 The team addressed the following questions on technical orders: 1. Are there any safety concerns in the USAF Technical Order System? 2. Are all of the books, manuals, and checklists used by personnel to maintain C-130 aircraft accurate and effective to ensure that safety is being maintained?

4.6.2 There are detailed procedures to ensure that all of these T.O.s are kept up to date and that any deficiencies discovered are corrected. Any crewmember or maintenance person can identify a deficiency by writing it up on the proper form--Form 847 for flight manuals and an AFTO Form 22 for maintenance manuals. These forms are submitted through channels to the System Program Office (SPO) who is charged with the responsibility for managing these T.O.s.

4.6.3 The BAR looked very closely at this process to ensure that all such deficiencies were being addressed in a timely manner to preserve flight safety. They found no unresolved deficiencies in this process, both for flight manuals and maintenance manuals. However, the same issues that exist with aircrew flight manuals exist with maintenance technical orders as well: a large backlog of changes to produce and post, multiple change pages to search through to accomplish even relatively simple maintenance actions, and scarce funding to solve the problem. The BAR is concerned that, while the veteran line craftsman may know where to look for all the changes when completing a repair, the less experienced maintainer may miss a critical step that is buried in a series of supplements, with potentially serious consequences. It will require a significant investment in resources and time, over $20 million and approximately two years, to fix the C-130 alone using current manpower levels to correct.

4.6.4 Initiatives are also underway to convert USAF technical manuals from the old, expensive and time-consuming paper format to the newer digital format. New CD-ROM technology offers many benefits, including a reduction in the annual $2.5 million cost of maintaining our T.O.s. This conversion faces many obstacles, including the cost of conversion as well as training and equipping field units to handle electronic data rather than paper.

4.6.5 Related Deficiencies and Concerns

DEFICIENCY: Maintenance units do not sump fuselage tanks on a regular basis leading to the possibility that water and contamination could collect within these tanks.

ON-GOING RESOLUTION: The BAR supports amendment of the T.O.s as necessary so that fuselage tank sumping is required at regular intervals.

Section 5.0

C-130 Mishap Review

5.1 USAF Mishap Data

5.1.1 The USAF C-130 has a very strong safety record. Introduced into the Air Force inventory in 1955, the C-130 has amassed over 14,400,000 flying hours. During this time, the Air Force experienced 142 Class A mishaps (aircraft destroyed or damaged beyond $1 million or economical repair, or where permanent disabling injury or loss of life occurs) resulting in 613 fatalities and the loss of 83 aircraft. An additional 45 aircraft were lost to combat. Since 1971, the Air Force has experienced 63 C-130 Class A mishaps resulting in the loss of 54 aircraft.

5.1.2 The C-130 has followed the USAF trend of fewer mishaps per flying hour over the years. The BAR attributes this to a number of factors including, but not limited to, increased systems reliability, improved components, improved training, and the USAF safety program.

5.1.3 The C-130 program implements the USAF safety program in two ways. The System Safety Group consists of all C-130 users and is focused on mishap prevention. The Material Safety Task Group tracks the status of all appropriate USAF C-130 mishap recommendations and ensures the appropriate resources are applied and progress is being made on the corrective actions resulting from these recommendations. Safety is also integral to C-130 training and the content of the technical orders.

Figure 5-1

USAF Historical Mishap Vs. C-130 Mishap Rates:

1957-1997

5.1.4 The cumulative class A mishap rate for the C-130 is 0.99 (class A mishaps per 100,000 flying hours). This safety record is noteworthy when considering the missions and environments in which the USAF flies the C-130 (see Section I, Operating Environments and Missions). The C-130 rate is well below the Air Force rate of 1.37 and comparable to the C-5 rate of 0.91.

5.2 Worldwide Mishap Data

5.2.1 The U.S. Navy and U.S. Coast Guard also fly C-130 aircraft. The Navy has flown C-130s since 1961. Their lifetime class A mishap rate (1961-1998) is 0.87 mishaps per 100,000 flying hours, but they’ve had zero class A mishaps since 1977. The Coast Guard only has flying hours available back to 1983. From 1983 to 1997, their class A mishap rate is 0.30 (only one mishap). Between 1961 and 1982 they experienced three other class A mishaps.

5.2.2 With almost 25 million C-130 flying hours world wide, there have been 284 aircraft lost to mishaps: 194 Class A mishaps, 14 ground mishaps, four other mishaps, and 72 lost in combat. Data on the causes of these mishaps (not including combat losses) is depicted in Figure 5-2. Of the approximately 2,100 aircraft built in the last 44 years, approximately 1,800 are still in service.

Figure 5-2

 

5.3 Uncommanded Power Reductions

5.3.1 Analysis of Reported Uncommanded Power Reductions. Table 5-1 shows the known reported incidents of uncommanded power reduction since the Air Force began keeping these records in 1983. Note that none of these are Class A mishaps, and that the list does not include the Portland King 56 mishap.

Table 5-1

Breakdown of 71 Reported Incidents:

Electromagnetic Interference (EMI) 03

Fuel Starvation 03

Synchrophaser 07

Aircraft Electrical System 24

Unknown 34

 

5.3.1.1 Electromagnetic Interference (EMI): EMI from the HF radio antenna accounted for three of 71, or 4% of the reported incidents. One incident resulted from an improperly connected HF antenna. Shielding has worked in keeping the number of electromagnetic interference incidents down.

5.3.1.2 Fuel Starvation: During the course of reviewing the reported C-130 power-loss incidents, three events were of special interest due to their apparent similarity to the Portland mishap. These events were clearly sequential engine power-loss events, not the traditional simultaneous engine power-losses historically associated with synchrophaser or electrically related power-loss events. It was postulated that these events were really fuel starvation events and an effort was made to learn more about them. Additionally, none of these events resulted in a mishap so the corrective actions taken by the crews were also of interest since the actions may help improve existing procedures. To learn more about each of these incidents, the team contacted the flight crews for each incident. In the process of examining the details surrounding these three events, another unreported event was discovered which also exhibited the symptoms of fuel starvation. This event was also examined, bringing the total looked at to four. A discussion of each of these incidents is contained in Section 5.4.

5.3.1.3 Synchrophaser: The synchrophaser accounted for only seven of 71 or 10% of the reported incidents. Of these seven incidents, three were due to water getting into the synchrophaser unit, two were due to interface wiring bundle problems, and two were due to internal synchrophaser problems. This is consistent with the fact that 90% of the synchrophasers returned to the depot from the field for deficiencies under the product quality deficiency report (PQDR) system tested within operational limits.

5.3.1.4 The PQDR is the unit’s way to get feedback from depot when they send a defective part in for repair. The unit requests PQDR action on a specific part by providing the specifics of the malfunction to the depot. The depot analyzes and repairs the part, then identifies in writing to the sending unit what they found. The synchrophasers examined by the depot were found to be within acceptable tolerance and adjusted back to centerline, then returned to the field. The small percentage of defective synchrophasers caused the team to look more toward other potential causes for engine rollback and other uncommanded power reduction phenomenon.

5.3.1.5 Aircraft electrical system - This system may have contributed to 24 of 71 or 34% of the reported incidents. The electrical system’s components may have fed faulty or fluctuating power, or data signals, to the synchrophaser or to the electrical controls within the propellers themselves. Possible problem sources include the failure of generators, generator control panels, and the essential AC bus. Faulty electrical system components may have also played a part in the majority of the 34 incidents with unknown causes, making it a category of considerable interest. The ongoing FMECA should reveal additional information on what part the aircraft electrical system plays as a potential cause of problems.

5.3.1.6 Unknown - Thirty-four of 71, or 48% of the reported incidents are classified as caused by unknown reasons. Most of these are strongly suspected to be caused by the aircraft electrical system (old synchrophaser interface wiring bundles, bad grounds, old power system powering newer components, etc.).

Figure 5-3

 

5.3.1.7 Since completing the installation of the solid state synchrophaser in June 1992, there have been no reported rollbacks attributed to internal failure of the synchrophaser and only four rollbacks with unknown causes. This indicates that efforts to clean up the electrical power and improve synchrophaser performance have been beneficial. Modifications include the constant voltage transformer (Dec 88 - Dec 93), solid state synchrophaser (Jan 90 - Jun 92), and HF antenna lead shielding (Mar 92 - Mar 98 [est.]). The ongoing FMECA should identify any additional potential problem areas with the aircraft electrical system.

Table 5-2

Breakdown of 71 Reported Incidents by Tail Number (Year of Manufacture):

55 - 01

56 - 03

57 - 02

58 - 00

59 - 00

60 - 00

61 - 05

62 - 03

63 - 08

64 - 12

65 - 07

66 - 02

68 - 05

69 - 05

70 - 01

72 - 00

73 - 03

74 - 12

78 - 00

79 - 00

80 - 00

81 - 00

82 - 00

83 - 00

84 - 00

85 - 01

86 - 00

87 - 00

88 - 00

89 - 00

90 - 00

91 - 00

92 - 01

93 - 00

94 - 00

95 - 00

96 - 00

 

(Note: Intervals between years reported [e.g. 75-77] reflect no C-130 purchases by USAF)

5.3.1.8 Only two of the incidents reported thus far occurred on aircraft built after 1974 (see Table 5-2). The majority of the reported incidents (63 of 71 or 89%) occurred on aircraft built and fielded between 1961 and 1974. The lack of incidents associated with newer aircraft, coupled with the fact that there have been only two incidents caused by internal failure of the solid state synchrophaser, combined to discount the solid state synchrophaser as a likely cause of the problems experienced.

 

Table 5-3

Breakdown of 71 Reported Incidents by C-130 Mission Design Series:

C-130A 04

C-130B 03

C-130E 26

C-130E (ESU) 01

C-130H-1 12

C-130H-2 01

C-130H-3 01

AC-130A 01

AC-130H 02

DC-130A 01

EC-130H 04

HC-130H 04

HC-130N 02

HC-130P 04

MC-130E 03

WC-130H 02

5.3.1.9 Basic C-130 aircraft (A, B, E and H models) accounted for 68% or 48 of the 71 incidents (see Table 5-3). These aircraft, however, comprise the overwhelming majority of the C-130 fleet (75.8% of the Air Force’s fleet, or 526 of 694 as of April 1, 1997). Our modified aircraft, with their additional systems installed, tend to have a higher percentage of reported incidents of RPM rollback (see Figure 5-4).

Figure 5-4

Fleet Composition vs. Incidents

 

5.4 Possible Fuel Starvation Incidents

5.4.1 Three of these 71 incidents, although initially reported as RPM rollbacks, were determined by the BAR to have occurred due to fuel starvation. Additionally, one other unreported incident was also determined to be caused by fuel starvation. In each case, this determination was made based upon the incident report (if reported), crew testimony, and system analysis. Each of these incidents is discussed below.

5.4.2 Spring 1991 Incident, HC-130N. This aircraft departed home station in the morning and refueled three helicopters. It landed at a second air field, refueled, and prepared to refuel helicopters again. In the afternoon, it refueled three helicopters in a short amount of time. During this swift refueling operation, the aircraft ended up in a "secondary fuel management" condition. The flight engineer accepted this position as a cost of being able to offload fuel to receivers rapidly. However, when refueling operations were complete, the flight engineer worked to get back into a primary fuel management position. This was accomplished by "scavenging" small amounts of fuel remaining in the auxiliary and external tanks, using the remaining fuel in the fuselage tank, and balancing main tank fuel with two main tank pumps on and the other two off. According to testimony, primary fuel management was achieved, all main tank pumps turned on, and the aircraft fuel panel in tank-to-engine configuration prior to the aircraft entering a low-level route for its return to home station.

5.4.2.1 After a short period of flight in the low-level route with light turbulence, one of the torque gauges began to fluctuate slightly. After confirming that this engine was not the master engine for the synchrophaser, the torque on number 3 engine gauge was observed to drop significantly. The remaining engines also began to lose power as well. Nearly simultaneously with the power-loss, the aircraft commander took control of the aircraft, initiated a climb, and the flight engineer began to execute the four-engine power-loss procedure.

5.4.2.2 While the flight engineer was executing the four-engine power-loss procedure, the load master stated, over the intercom, that the number 1 engine had flamed out. The aircraft commander visually scanned the number 1 engine and confirmed its condition. The flight engineer, while on the floor by the pilot’s seat preparing to pull the synchrophaser’s AC circuit breaker, also confirmed the condition of the number 1 engine. The copilot, reacting to the load master’s observation and the pilot’s verification was ready to feather the number 1 engine and was awaiting confirmation from the flight engineer before doing so. The flight engineer returned to his seat without pulling the synchrophaser’s DC circuit breaker. Confirmation to feather the number 1 engine was not given to the copilot because it appeared that power was beginning to return to the other engines. Power did return to number 2, number 3 and number 4 engines and number 1 started as if the crew were performing an air start. All engine power was completely restored.

5.4.2.3 The crew diverted to a nearby airfield without further incident. Specific maintenance actions performed on the aircraft and the results of fuel samples taken from the aircraft and the three helicopters are unknown. This aircraft was equipped with a tube-type synchrophaser.

5.4.2.4 According to the testimony provided the BAR, during the period of the rollback, all four low fuel pressure lights were illuminated, as were the number 1, number 3 and number 4 engine generator-out lights. With the number 2 generator turned off (a result of executing the four-engine power-loss procedure), and the other generator-out lights illuminated, there should have been no electrical power being generated by this airplane. The BAR knows this cannot be true, otherwise the aircraft low fuel pressure lights (which receive power from the DC essential bus), would not have been illuminated. Since the low fuel pressure lights were illuminated, at least one generator must have been on-line and producing power. With only one generator on-line, the number 2 main tank pump (which receives power from the essential AC bus), and the number 3 main tank pump (which receives power from the Main AC bus) must have been running--provided they were turned on. If they had been turned on and running, they would have been producing pressure, thus extinguishing the number 2 and number 3 low fuel pressure lights. Since the number 2 and number 3 low fuel pressure lights were illuminated, the BAR believes that the number 2 and number 3 main tank pumps were turned off. With the other engines behaving similarly, the BAR also believes that those main tank fuel pumps were turned off as well.

5.4.2.5 This last conclusion is based upon evidence that, upon the flight engineer returning to his seat, all four main tank boost pumps were cycled off and then back on. If there had been an electrically related problem, it is doubtful that this action would have corrected the situation. The BAR believes that the main tank fuel pump switches were off and that by "cycling" them, they were actually turned on, providing a positive flow of fuel to the engines, resulting in the restoration of all engine power. It is believed that instead of the two main tank pumps being turned back on prior to entering the low-level route, the two that were already on were actually turned off. Even though this aircraft was flying a low-level route, it is believed that pressurized cabin air entered through an empty fuselage tank and worked its way out to the engines. This could have happened, provided the low-level route was being performed over high terrain and cabin pressure was set at a typical value of 1,000 feet.

5.4.2.6 With this air in the manifold, it eventually worked its way out to all four engines resulting in the engine power-losses. It is believed that this air has the potential to adversely affect critical engine fuel control components, disturb/disrupt combustion within the engines, or cavitate the engine-driven fuel boost pumps. By turning the main tanks pumps on, it is believed that the source of the air was eliminated, and once the existing air was purged from the fuel supply manifolds, power to the engines was restored. This aircraft did not experience any further problems similar to what this crew experienced.

5.4.3 Fall 1992 Incident, HC-130P. This incident occurred during an aircraft ferry mission, flown to return the aircraft to home station. While cruising at approximately FL 180 (18,000 feet), one hour into the sortie, the pilot noticed torque, fuel flow and TIT start to decrease on the number 1 engine. A short while later, the number 3 engine exhibited similar problems. Then number 2 and number 4 engines started to lose power as well. The flight engineer initiated the four-engine power-loss procedure. As the final steps of the procedure were accomplished, the following results were obtained: pulling the synchrophaser’s AC circuit breaker resulted in no affect while pulling the synchrophaser’s DC circuit breaker apparently restored power to all engines. The crew then flew one hour back to home station, the nearest field, without further incident.

5.4.3.1 Maintenance could not find anything definitively wrong with this aircraft but removed and replaced the aircraft’s solid state synchrophaser followed by uneventful engine runs. The same crew then flew this aircraft without further problems.

5.4.3.2 Testimony provided the BAR revealed that the flight engineer’s personal technique of turning off the main tank fuel pumps was utilized when feeding all four engines from a fuselage tank. In this case, the crossfeed separation valve was open, all four engines were being fed from the fuselage tank, and all the main tank pumps were turned off. After the fuselage tank empty light had flickered for a few seconds, the second pump in the fuselage tank was turned on and allowed to run briefly before the aircraft was transitioned to crossfeed from the external tanks. To accomplish this, the external tank pumps were turned on, the fuselage tank pumps turned off, the crossfeed separation valve was closed, and the main tank pumps turned on. While this was being accomplished, all four engines began to lose power as described above.

5.4.3.3 The BAR believes that, for the period of time between the fuselage tank empty light first flickering and turning on the external tank pumps, pressurized cabin air entered the fuel supply manifold via the empty fuselage tank. With this air in the manifold, it eventually worked its way out to all four engines resulting in the engine power-losses. It is believed that this air has the potential to adversely affect critical engine fuel control components, disturb/disrupt combustion within the engines, or cavitate the engine-driven fuel boost pumps. By transitioning to a new source of fuel (i.e., the external tanks), it is believed that the source of the air was eliminated, and once the existing air was purged from the fuel supply manifolds, power to the engines was restored. Lastly, it is believed that pulling the synchrophaser’s DC circuit breaker and the return of engine power coincidentally correspond to the time when the last of the air finally worked its way out of the crossfeed manifold. This aircraft did not experience any further problems similar to what this crew experienced.

5.4.4 Winter 1992 Incident, HC-130P. This incident occurred during a ferry mission. While cruising somewhere between FL220 and FL250 all the engines began to sequentially lose power. The exact order of the power losses could not be determined but torque losses of approximately 2,000-3,000 in-lbs were seen on all the engines. The crew did not run any portion of the four-engine power-loss procedure. Instead, they came off crossfeed and went tank-to-engine and all engine power was restored. Just prior to engine power-loss, the crew had been crossfeeding the fuselage tank to all four engines. The fuselage tank was also running very low on fuel. The crew suspected that they had fuel contamination, but results of fuel testing and fuel filter checks are not known.

5.4.4.1 In this incident, it is believed that the main tank pumps were off and when the fuselage tank ran low on fuel, pressurized cabin air was allowed to enter the fuel supply manifold via the empty tank. With this air in the manifold, it eventually worked its way out to all four engines resulting in the engine power-losses. It is believed that this air has the potential to adversely affect critical engine fuel control components, disturb/disrupt combustion within the engines, or cavitate engine-driven fuel boost pumps. By returning to tank-to-engine configuration, it is believed that the source of the air was eliminated, and once it was purged from the engine feed lines, power to the engines was restored.

5.4.5 Summer 1997 Incident, C-130H. This incident occurred during the climb portion of a cross-country sortie. The aircraft was climbing through FL220 headed for FL240. The aircraft was being crossfed from the external tanks. Specifically, the left-hand external tank was feeding number 1 and number 2 engines while the right-hand external tank was feeding number 3 and number 4 engines. The crossfeed separation valve was closed. While passing through FL220, small torque fluctuations were observed on the number 1 engine. This quickly progressed into larger power fluctuations on the remaining engines. The crew observed fluctuating torque, TIT and fuel flow on all these engines. The aircraft was leveled off, and the flight engineer, knowing the Portland mishap happened only months before, began executing the four-engine power-loss procedure. The flight engineer never completed the procedure--neither synchrophaser AC nor DC circuit breaker was ever pulled. Instead, the flight engineer came off crossfeed, went tank-to-engine, and engine power was restored.

5.4.5.1 The external tanks were low on fuel, indicating approximately 200 lbs each, just prior to engine power being lost. After restoring engine power, the aircraft was flown for several more hours without incident. Fuel contamination in the external tanks was suspected by the crew, but feeding one engine exclusively from one external tank on the ground for several minutes did not result in any anomalies. The external tanks were also "sumped" in order to check for contamination. None was observed. The aircraft was refueled and the cross-country continued without further incident. In total, three sorties were flown by the same crew after the power-loss event and no engine anomalies were noted during any of these subsequent sorties.

5.4.5.2 In this incident, it is believed that the main tank pumps were off and when the external tanks ran low on fuel, air entered the fuel supply manifold and eventually worked its way out to the engines. It is believed that air has the potential to adversely affect critical engine fuel control components, disturb/disrupt combustion within the engines, or cavitate engine-driven fuel boost pumps. By returning to tank-to-engine configuration, it is believed that the source of the air was eliminated, and once it was purged from the engine feed lines, power to the engines was restored.

5.4.5.3 The BAR’s belief that main tank pumps were off is supported by testimony that the flight engineer used a personal technique on the ground prior to flying local sorties (where external tank fuel is not required to complete the sortie), which was to "dry-drain" the external tanks. This technique involved feeding the engines from the external tanks, with the main tank pumps turned off, until all the fuel in the external tanks was exhausted. With this ground technique established and performed on the ground, it is believed that a habit pattern was formed, and the personal technique was eventually utilized in flight and led to the incident just described.

Section 6.0

King 56 Accident Summary

6.1 Established Facts

6.1.1 The accident investigation report provides the summary of known facts surrounding the crash of HC-130P, tail number 64-14856 and the death of 10 of the 11 people on board. This discussion will focus only on the aircraft and those operational and logistics issues that could potentially cause four engines to fail.

6.2 Flight Operations

6.2.1 Based upon digital flight data recorded (DFDR) information, the mishap aircraft departed Portland IAP at 1720 PST on 22 Nov 96 on an instrument flight rules (IFR) flight en route to North Island Naval Air Station. The purpose of the sortie was to conduct an overwater navigation evaluation. King 56 began the sortie with a normal takeoff, departure and climbout. One hour and 24 minutes after takeoff in level flight at FL 220 the mishap sequence began with the engineer commenting on a torque flux on the number 1 engine. Nothing on the cockpit voice recorder (CVR), the DFDR, or the survivor’s testimony suggested any unusual events prior to the engineer’s comment. Over the next three minutes, the operations of all four engines became unstable and eventually failed. Crew actions during these critical three minutes are known only by verbal comments on the CVR and the survivor’s testimony. The following discusses what we know of those actions.

6.2.2 The engineer called for number 1 propeller to be placed in mechanical governing. This would normally remove electrical inputs to the propeller through the synchrophaser. The pilot then called for all four propellers to be placed in mechanical governing. This action was consistent with treating this emergency as a four-engine rollback. There is no indication on the DFDR or the CVR as to whether or not the crew selected mechanical governing on any of the remaining three propellers. At the same time the crew was analyzing the emergency, they also declared an in-flight emergency with Oakland ARTCC and turned the mission aircraft east to proceed toward Kingsley Field, Klamath Falls, OR, approximately 230 miles away and approximately 80 miles from the coast. The Radio Operator radioed the USCG Humboldt Bay Station and notified them of the in-flight emergency. During the turn toward the shore the number 3 and number 4 engines once briefly recovered most of their torque. These increases are recorded by the flight data recorder. When the RPM on number 3 (the aircraft’s last functioning engine) finally decreased below 94% RPM the last generator producing electrical power dropped off line due to low frequencies. As a result, at 1846 Pacific Standard Time all electrical power was lost. After a brief period, power was restored to the equipment powered by the battery bus. From this point on, the aircraft glided to the attempted ditching. There is no record of that portion of the flight, except the survivor’s testimony.

6.2.3 Other issues of significance. There are several extant records that document fuel information. The AFTO Form 151A indicates that King 56’s first sortie on 22 Nov 96 landed with 12,000 lbs of fuel. The aircraft was then refueled. Fuel truck records indicate an onload of 4,088 gallons for the second sortie, which is approximately 27,800 lbs. This data is consistent with an initial fuel load of 40,000 lbs on the mishap sortie. However, the Form F (AFTO Form 365-4) indicates a fuel load of 39,000 lbs. The fuel load is normally documented in the aircraft records, AFTO Form 781, which were lost with the aircraft. The AFTO Form 781 is normally the principal place to record fuel distribution, so the BAR was unable to confirm the actual distribution of the initial fuel load. The Form F is the aircraft weight and balance form completed before each flight and it normally records the total fuel and its distribution. The Form F indicates that fuel was in the main, auxiliary and external tanks.

6.2.4 Computerized maintenance records indicate that the right-hand auxiliary tank had a leak, and that the left-hand fuselage tank had an indicator problem, as did one external tank. While unusual, this combination of inoperative gauges is permissible to fly in accordance with regulations if certain procedures are followed. These restrictions would include not fueling the leaking tank, and in the case of the external tanks, lateral weight limitations require that the external tanks weigh the same amount. In this case, aircrews must verify the tanks full or empty. This would force the crew to either fuel them completely full, or not fuel them at all. These are the only two ways to be completely certain that the tanks weigh the same.

Table 6-1

King 56 Fuel Tank Malfunctions, Options, and Capacities

FUEL TANK MALFUNCTION FUELING FUEL CAPACITY

OPTIONS IN POUNDS

OUTBOARD MAINS* NONE STANDARD 6,834

INBOARD MAINS NONE STANDARD 7,322

LEFT AUXILIARY NONE STANDARD 5,598

RIGHT AUXILIARY LEAK NO FUEL 5,598

LEFT EXTERNAL INOP INDICATOR FULL OR EMPTY 8,359

RIGHT EXTERNAL NONE SAME AS LT EXT 8,359

LEFT FUSELAGE INOP INDICATOR NO FUEL 11,016

RIGHT FUSELAGE NONE STANDARD 11,016

*Refueling Pods Installed

6.2.5 The Form F and maintenance data conflict. The Form F indicates fuel in the external tanks, but not enough fuel to fill the tanks. The Form F also indicates no fuel in either fuselage tank.

6.2.6 Two possibilities exist: the Form F was either in error or correct. The BAR explored the first possibility. There was no indication that the external tank entry was an error because the center of gravity calculations match those for external tanks shown on the Form F. Alternatively, the loadmaster could have anticipated one fuel load, but discovered another different fuel load had actually been put on the aircraft. Because the variation in center of gravity was only one and a half percent from that expected, there would have been little incentive to correct the error. Had the Form F been wrong, failure to correct the error would have had no safety implications. Finally, there exists the possibility that the fuel was put in the external tanks, either by error, or because the maintenance records were in error and the external tanks were in fact operational. While we cannot conclusively rule out either possibility, interviews with other engineers, loadmasters, and maintenance personnel caused the BAR to believe strongly that the fuel was put into the fuselage tank and not the external tanks.

6.2.7 The mishap sortie was the second of the day for the aircraft. The mishap aircraft flew another training sortie earlier in the day. The pilot’s and radio operator’s integrated display control unit (IDCU), a portion of the Self Contained Navigation System, were replaced after the first sortie. Ultimately, the IDCUs were determined not to be defective. Discussions with maintenance personnel indicated a normal thru-flight was accomplished. No unusual maintenance was performed on the aircraft.

6.2.8 Two issues were raised about the mishap aircraft. The first concerned the micro-burst which struck the aircraft while parked on the Davis-Monthan AFB, AZ, ramp in May 1994. The major mircoburst damaged the number 4 propeller, the right wing aft lower spar cap, and the right inflight refueling pod and pylon. The number 4 engine and propeller were replaced, as were the right refueling pod and pylon. The wing spar was also repaired. No documents were found to verify any additional inspections specifically conducted with respect to this repair. It is appropriate to note that these repairs were completed in conjunction with programmed depot maintenance which was completed in July, 1995.

6.2.9 The second issue, raised with both unit engineers and maintenance personnel, was whether any maintenance was performed on all four engines or propellers on that aircraft in recent memory. That question generated two responses. There was a write-up of the aircraft pulling in one direction during taxi. After performing extensive maintenance, the problem was ultimately resolved by the unit maintainers trading the number 1 and number 4 propellers. This was done in September 1996.

6.3 Scenario Introduction

6.3.1 The team’s approach to understanding the King 56 mishap was to ask what circumstances could cause a C-130 to lose all four engines. A conscious effort was made not to approach the issue sequentially, but to come up with as many theories as could potentially explain the mishap, however unlikely, and then evaluate scenarios based on the available data. The following is a general discussion of some critical aspects of aircraft operations and the clues present in the King 56 data that point toward one scenario or another. For each scenario presented, the BAR will offer both corroborative and rebutting evidence as they apply.

6.3.2 Fuel Starvation: In its simplest form, fuel starvation is merely an inadequate supply of fuel to the engines which lasts long enough for an engine to flameout. Fuel starvation can occur if the fuel supply simply ceases to flow to the engines, is sufficiently restricted, or if air or water is introduced into the fuel supply lines leading to the engines. Scenarios outlining how the cessation of, or restriction of, fuel flow, or the introduction of air or water into the fuel supply manifold could have happened are discussed below. However, fuel starvation clues from the Portland mishap, and C-130 fuel system information needed to understand fuel-related scenarios, are only presented once.

6.3.3 Fuel Starvation Clues: There are at least five clues from the Portland mishap that suggest fuel starvation. Prior to any hint of a problem surfacing, all four engines are producing approximately 11,000 in-lbs of torque. The problem was first recognized at 18:43:51 after torque on the number 1 engine had rapidly dropped to approximately 5,000 in-lbs. Within 10-15 seconds, all four engines experienced varying degrees of torque reduction.

6.3.3.1 Clue One: At 18:44:02, the flight engineer stated that fuel flow to the number 1 engine had "…gone to s---."

6.3.3.2 Clue Two: At 18:45:07, the flight engineer stated that he had lost fuel flow to the number 2 engine. As the sequence continued to 18:45:10, the number 1 engine was shutdown, the number 2 engine indicated negative torque, and the torques on numbers 3 and 4 were 3,500 and 7,500 in-lbs, respectively. Moments earlier, the torques for numbers 3 and 4 had been even lower. At 18:45:12, the pilot initiated a left hand turn toward the California coast.

6.3.3.3 Clue Three: Shortly after initiating the turn, the torques on engines 3 and 4 began to recover. By 18:46:00, the torques on numbers 3 and 4 recovered briefly to 10,000 and 11,000 in-lbs respectively. Flight test data show that this surging recovery is consistent with fuel being intermittently supplied to the engines. Shortly after King 56 completed the turn, torques on number 3 and 4 engines fell again, but this time rapidly.

6.3.3.4 Clue Four: Torque on engine number four recovered again, albeit briefly, for the last time at 18:46:23. This torque recovery followed a brief dip of the right hand wing tip. Once again, flight test data show that this surging recovery is consistent with fuel being intermittently supplied to the engines.

6.3.3.5 Clue Five: Despite the fact that torque fluctuated widely, all engine RPM indications remained normal throughout the whole sequence. This is a result of proper propeller blade angle governing. Individual RPMs only began to drop when their respective engines produced insufficient torque to maintain the engine and propeller at 100% RPM.

6.3.4 Initial Fuel Configuration: Based on the Form F and fuel servicing documentation, the BAR believes the mishap aircraft was serviced to approximately the following fuel load:

Table 6-2

King 56 Probable Fuel Loading

No. 1 Main No. 2 Main Lft Aux Rt Aux No. 3 Main No. 4 Main

7,000 lbs 7,000 lbs 4,000 lbs 0 lbs 7,000 lbs 7,000 lbs

Lft External Rt External

0 lbs 0 lbs

Left Fuselage Right Fuselage

0 lbs 8,000 lbs

6.3.5 The BAR believes the left hand external tank was not used because the fuel quantity indicator drove off scale, low end, when its forward boost pump was turned on. Fuel was not placed in the right hand external tank in order to maintain lateral balance. The right hand auxiliary tank was not used because it leaked around the cavity drain. And finally, the left hand fuselage tank was not used because the tank’s fuel quantity gauge, not the one on the flight deck, rotated backwards.

6.3.6 Regardless of the source of the fuel on King 56, calculations show that the total amount of fuel required to fly the mishap profile is approximately 8,400 lbs. These calculations were performed using T.O. 1-C-130H-1-1, and the specific amount of fuel required for each phase of the flight for the mishap sortie is shown in Table 6-3 below:

Table 6-3

Calculated Fuel Requirements for King 56

 

Time

(minutes)

Burn Rate

(1,000 lbs/hr)

Fuel Used

(1,000 lbs)

Fuel

Remaining

Start, Taxi

15

3.00

0.75

39.25

Takeoff

2

Tables

0.30

38.95

Climb

20

Tables

2.35

36.60

Cruise

64

4.68

5.00

31.60

6.3.7 The validity and accuracy of these calculations was investigated further in a C-130 simulator where all the specifics for the mishap sortie (i.e., aircraft gross weight, aircraft drag, weather conditions, etc.) were input into the simulator. The simulator flight crew was then tasked to fly the mishap sortie profile. This included starting engines, taxi to the runway, taking off, climbing, leveling off and cruising, and performing all required checklists. Based upon DFDR data from King 56, the total time to perform engine start, taxi and takeoff in the simulator was nearly identical to that at Portland. Simulator time-to-climb was slightly faster than that on the DFDR--18:10 and 18:00 minutes in the simulator versus 20:00 minutes for King 56. Cruise performance (i.e., indicated airspeed and engine torques) was eventually "matched" with appropriate positioning of the throttles.

6.3.8 Fuel requirements from the simulator were very similar to those shown in Table 6-3. Fuel required for start, taxi and takeoff in the simulator was nearly 800 lbs versus 1,050 pounds calculated. Fuel required for climb in the simulator was nearly 2,100 lbs versus 2,350 calculated. Fuel flow readings taken during the cruise phase in the simulator averaged at 4,700 lbs/hr for all engines versus 4,680 lbs/hr calculated.

6.3.9 The 250 lb differences between simulator results and calculations for both the start, taxi, takeoff and climb phases are not considered significant given the certainty of the data used (i.e., aircraft gross weight, aircraft drag, weather conditions, engine performance, etc.) and the fidelity and layout of the performance charts themselves. In short, the simulator verified, within a given tolerance, that the calculated amount of fuel required to fly the mishap profile presented in Table 6-3 is correct.

6.3.10 Fuel System: An extensive fuel system positive fuel flow check is performed by the flight engineer prior to the first sortie of the day and after the aircraft is refueled to ensure proper engine operation. In addition, two pressure gauges, four low fuel pressure warning lights, and several tank empty caution lights are exercised during this check. If an aerial refueling off-load is planned, an aerial refueling manifold pressurization check must also be performed.

6.3.11 Fuel system operation is categorized in one of two ways. Fuel sent directly from the main tanks to their respective engines is called "tank-to-engine" operation. In this case, the number one main tank feeds only the number one engine, and so on for the other three engines. During tank-to-engine operation, fuel from other tanks (i.e., external, auxiliary and fuselage) is not used. The alternate method of fuel system operation is called "crossfeed." In this situation, any of the other "non-main" tanks can feed any of the engines. It is also possible to crossfeed from the main tanks as well. All crossfeed operations involve the use of the crossfeed manifold. Crossfeeding from the fuselage tanks also involves the use of a fuselage tank manifold, the refuel/dump manifold, and the right hand external crossfeed manifold. Prior to crossfeeding operations, the manifolds must be primed--that is purged of all air. Priming procedures are contained in T.O. 1C-130(H)H-1, Section 7. This procedure basically entails turning on the source pump(s), holding the crossfeed prime button depressed which opens a valve to the number two main tank, and the crossfeed separation valve, and allowing sufficient time for the pump(s) to fill the manifold while exhausting any air/fuel mixture into the number 2 main tank.

6.3.12 The fuel pumps in the auxiliary, external and fuselage tanks remain turned off unless they are being used. This is not true for the main tanks. For the main tanks, the pumps remain on whether the main tanks are being used or not. Exceptions to this "rule" are made for handling fuel imbalances (i.e., one main tank pump off) and emergencies (i.e., two main tank pumps off). Under normal operating conditions, there is no reason to intentionally turn off three or four main tank pumps at the same time in flight. Always operating with the main tank pumps on ensures that the engines will receive an uninterrupted pressurized supply of fuel, should an unplanned event occur during crossfeed operations, such as: an auxiliary, external, or fuselage tank running dry; an auxiliary, external, or fuselage tank pump fails; or, the crossfeed or refuel/dump manifolds fail or are somehow blocked.

6.3.13 Main tank pump output pressure is 15-24 psi. Auxiliary, external and fuselage tank pump output pressure is 28-40 psi. By virtue of the differences, when the auxiliary, external or fuselage tanks are selected on crossfeed, they will feed the engines even though the main tank pumps are on. Their higher pressure overrides the output pressure from the main tanks, thereby preventing fuel flow from the main tanks.

6.3.14 Low fuel pressure warning lights illuminate when aircraft fuel pressure to their respective engine falls below 8.5 psi. Tank empty caution lights for the auxiliary, external, and fuselage tanks come on when pump output pressure for their respective tank falls below 23 psi. The main tanks do not have tank empty lights since they should always contain some amount of fuel.

6.3.15 Only main tanks have the ability to gravity feed. Gravity feed operation is checked in flight during functional check flights (FCF). During the gravity feed check, the aircraft is in tank-to-engine and fuel flow to all engines is established. Then the number one main tank pump is turned off. Proper engine operation under gravity feed is confirmed, and the number one main tank pump is turned back on. This process is repeated for the remaining main tanks in sequence and takes approximately one minute for each. The HC-130 aircraft also check gravity feed as part of the positive fuel flow check prior to flight.

6.3.16 In this mishap, there are essentially two basic sequences in which the flight engineer might have planned to use fuel. One sequence uses the mains first (for taxi, takeoff, and some portion of the climb), followed by the left hand auxiliary, right hand fuselage, and then back to the main tanks again. Alternatively, he could have used the mains, followed by the right hand fuselage, left hand auxiliary, and then back to the main tanks. Conventional wisdom says that the former method would most likely have been chosen. This is due to the fact that auxiliary tanks have only one pump and there is no possibility, including gravity feed, to obtain fuel from them in the event of a pump failure. Since the planned mission was over water, the crew would want to burn auxiliary tank fuel early or know as soon as possible if that fuel would be unusable (i.e., trapped) during the mission.

6.4 Scenarios Evaluated

6.4.1 The BAR identified 20 possible scenarios that could have occurred on 22 Nov 96 resulting in the loss of HC-130P, 64-14856 and all but one of the people aboard. Each of these possible scenarios is presented below and includes: (1) details of the scenario or a brief synopsis, (2) a numbered step-by-step failure sequence including detailed information for each step, when appropriate, and (3) corroborating and rebutting evidence, data and rationale. For brevity, the numbered step-by-step failure sequences for many scenarios do not include detailed information because this information was already presented in a previous scenario. The same is true for repeated corroborating and rebutting evidence, data and rationale. Additionally, the reader is referred to summary write-ups and more detailed documents when appropriate. This same format is also used for additional physical evidence needed to further corroborate or rebut each scenario.

6.4.1.1 Scenario Number 1. Left Hand Auxiliary Fuel Tank Run Empty

6.4.1.1.1 Scenario Details: With the preceding fuel load in Table 6-2, it is presumed that the engines fed from their respective main tanks for approximately the first 33 minutes of flight. For roughly the next 51 minutes, it is postulated that the engines were fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario.

 

Time

(min)

Fuel Used

(k lbs)

Fuel Source, Duration and Quantity Used
Start, Taxi

15

0.75

Tank-to-Engine, 15 min, 750 lbs
Takeoff

2

0.30

Tank-to-Engine, 2 min 300 lbs
Climb

20

2.35

Tank-to-Engine, 20 min, 2350 lbs
Cruise

64

5.00

Tank-to-Engine, 13 min, 1000 lbs then Left Hand Auxiliary, 51 min, 4000 lbs

Table 6-4: Fuel Burn Profile for Scenario Number 1

Fuel flow to the engines may have ceased in the following manner:

6.4.1.1.1.1 All the main tank pumps are off. Turning all the main tank pumps off is not an acceptable technique because positive fuel flow to the engines is not ensured in the event certain fuel system events, like those discussed earlier, occur. This technique is not taught to flight engineers during formal training, but the BAR identified several instances where its use was confirmed or strongly suspected. Additionally, the main tank pumps could have been inadvertently left off. The BAR discovered instances where this has occurred. Whether the pumps were off intentionally or inadvertently is not important. The key point is that the switches were in the off position. Lastly, all four main tank pumps could have failed or lost their power sources (each of the four main tank pumps has a different AC electrical power source) during the mishap sortie resulting in the pumps not operating. Although theoretically possible, this did not happen to King 56 because the DFDR and the CVR were continually powered until the last generator fell off line..

6.4.1.1.1.2 All the engines are being crossfed from the left hand auxiliary tank and it is pumped empty. Normally, flight engineers transition from tank-to-engine to crossfeed shortly after takeoff. Given that King 56 contained 40,000 lbs of fuel and only 20,000 lbs was planned for use on the sortie to Naval Air Station North Island, there may have been no urgency to transition to crossfeed operations. Additionally, the perceived presence of crossing air traffic, identified by Seattle Control during the climb to FL220, may have delayed the transition to crossfeed operations if the flight engineer helped scan outside the cockpit. For these reasons it is presumed that tank-to-engine was utilized for the first 33 minutes of flight before crossfeeding from the left hand auxiliary tank for the remaining 51 minutes.

6.4.1.1.1.3 Illuminated fuel warning/caution lights are either not seen or not believed. If the left hand auxiliary tank was pumped empty, five warning/caution lights on the overhead fuel panel should illuminate nearly simultaneously. They are the four low fuel pressure warning lights as well as the left hand auxiliary tank empty caution light. Although the fuel panel is not in an ideal location, these warning/caution lights should have been visible to the aircrew. However, they may not have been seen or acted upon for several reasons. First, the crew may have been too focused on the engine instruments and did not see these illuminated overhead warning/ caution lights. Second, since this was a night over water navigational training/evaluation mission, it is possible the warning and caution light switch may have been in the DIM position making the lights less apparent. Third, the survivor testified that the flight engineer had been reading a book prior to the problem surfacing. It is possible his eyes may have been slow to adjust to the darker cockpit surroundings thereby increasing the time required before he could see the overhead warning/caution lights. If the warning and caution light switch was in DIM, this situation would only be further aggravated. Lastly, even if the five fuel warning/caution lights were seen, it is possible that they were not recognized as the early warning signs of an impending fuel starvation. Instead, it is possible they may have been viewed as indications resulting from either a bleed air or an electrical problem. We know from the cockpit voice recorder that the pilot mentioned that they were perhaps dealing with a bleed air or an AC problem.

6.4.1.1.1.4 Gravity feed does not establish itself from the main tanks. When the left hand auxiliary tank (or any crossfed tank for that matter) runs empty, it is commonly believed that main tanks will automatically gravity feed to the engines. Despite the fact that the ability to gravity feed is checked, this check does not indicate that gravity feed can be established from the main tanks when previous fuel flow to the engines was through the crossfeed manifold. During the gravity fuel flow check, flow to a particular engine is first established with its associated main tank pump and then that pump is turned off. Fuel flow continues because a direct flow path from the tank to the engine has been established and this flow has momentum. This check in no way involves the crossfeed manifold. With a flow path established in the crossfeed manifold, some of the tank-to-engine flow path contains stagnant fuel which has no momentum. In this case, it is not only necessary to establish a new flow path (i.e., tank-to-engine), but its velocity must be increased sufficiently so that engine fuel flow demands can be met. If they are not met, the engine will initially lose power. If this condition persists long enough, the engine may flameout. There is no data to show that gravity feed can be established at all points in the aircraft’s operating envelope given that the main tank pumps are off and flow from the crossfeed manifold ceases.

6.4.1.1.1.5 Air enters the fuel supply manifold and is delivered to all four engines. Air in a fuel supply line has the potential to adversely affect critical engine fuel control components, disturb/disrupt combustion within the engines, or cavitate engine boost pumps. A small amount of air can be readily consumed by an engine and no one is aware this has occurred provided there is no loss in power. If the amount of air were greater, it may adversely affect the fuel control, adversely affect the temperature datum system, or disturb combustion within the engine temporarily causing the engine to lose power. If the amount of air were greater yet, it may disrupt combustion within the engine long enough to result in a flameout. However, at some point a large enough amount of air will cavitate an engine driven fuel pump, disrupting fuel flow and causing the engine to flameout. The precise failure mechanism, due to an undetermined amount of air introduced into the fuel supply manifold, is not known.

6.4.1.1.1.5.1 If all the main tank pumps are off and the left hand auxiliary tank is run empty, it is possible that either an adequate gravity feed will not establish itself at 22,000 feet or air will enter the crossfeed manifold resulting in multiple engine flameouts. T.O. 1C-130(H)H-1, page 3-24 states, "If a partial tank and an empty tank are on crossfeed with the boost pump inoperative in the partial tank, the engine being fed from the empty tank will be starved by air being drawn into the fuel line." Or stated more specifically in terms of this scenario, if the main tanks and an empty auxiliary tank are on crossfeed with the boost pumps failed or off in the main tanks, the engine being fed from the empty auxiliary tank will be starved by air being drawn into the fuel line. The BAR has been unable to uncover any existing test reports or analysis that substantiates this sentence in T.O. 1C-130(H)H-1.

6.4.1.1.1.6 All four engines eventually flameout. If no corrective actions were taken to reestablish fuel flow to the engines, all four engines would flameout. The primary corrective action necessary is the immediate restoration of positive fuel flow to the engines. This could be accomplished by turning the main tank fuel boost pumps on and returning to tank-to-engine.

6.4.1.1.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section 5, the incident history and continuing possibility that main tank pumps can be inadvertently left off, and the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB and Air Force testing at Edwards AFB). See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.1.2.1 The flight test performed at Edwards AFB rebuts this scenario. Although engines being crossfed from a left hand auxiliary tank when it is run empty experienced torque fluctuations on the ground, torque fluctuations were not observed in flight. Additionally, analysis of radar information reveals that there was no traffic close to King 56 during its climb. This makes it less likely that the flight engineer was scanning outside the cockpit thereby delaying the transition from tank-to-engine to crossfeed operations. The flight engineer had sufficient time during the two minute hold down at 15,000 feet to transition from tank-to-engine to crossfeed operations. Lastly, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off.

6.4.1.1.2.2 Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section. From the recovery videos, this section of the wing contains the crossfeed separation valve, the left hand auxiliary tank crossfeed valve and the number 2 main tank crossfeed valve. It probably also contains the number 1 main tank crossfeed valve. These are four of the six valves that would normally be open if the left hand auxiliary tank was crossfeeding to all four engines. The other two valves (the number 3 and number 4 main tank crossfeed valves) are no longer attached to this piece of wreckage. All of these valves are DC powered, and upon the loss of the last engine generator, their positions are captured. Since the cockpit voice recorder is devoid of any discussion of engineer overhead fuel control panel actions, the BAR believes that the valves are in the same positions as when the power loss first started. The position of these valves will help determine the source of fuel to the engines upon the loss of the last engine generator.

2. The Forward Fuel Control Panel and Auxiliary Fuel Panel. These panels contain numerous, lights, switches, control knobs and fuel quantity gauges. The lights, switches and control knobs are of little interest because they could have, and probably were, moved several times in an effort to restart the engines during the unpowered descent to the ocean. However, the fuel quantity gauges do not respond to manipulation of these switches and knobs. They only respond to fuel quantity within the tanks. These gauges are AC powered and, upon the loss of last engine generator, retain their last reading. Therefore, the final fuel state on the aircraft might be determined from these gauges.

3. Both Fuselage Tanks. These tanks each contain a control panel used for ground refueling. This control panel also contains a tank fuel quantity gauge. The gauges from both of these tanks are desired for the same reasons the cockpit fuel gauges are desired. Although one of these tanks was initially fueled and the other empty, it is difficult to distinguish between the two tanks making recovery of both tanks desirable.

6.4.1.2 Scenario Number 2. Right Hand Fuselage Fuel Tank Run Empty

6.4.1.2.1 Scenario Details (Variation A): This scenario is a variation of scenario number 1. In this case, the supposition is that the right hand fuselage tank is run empty instead of the left hand auxiliary tank. This could happen in one of two ways. First, with the preceding fuel load in Table 6-2, it is presumed that the engines fed from their respective main tanks for taxi, takeoff, and approximately 10 minutes into climb before transitioning to crossfeed operations. In this case, it is postulated that the engines were crossfed fuel from the right hand fuselage tank for the remainder of the sortie. To fly the remaining 10 minutes of climb and 64 minutes of cruise at FL220, it is estimated that 6200 lbs of fuel is required, 1800 lbs less than that believed to be in the right hand fuselage tank. See Table 6-5 for fuel-related details about each phase of the sortie for this scenario. With fuel quantity gauging/indicating failures, it is possible that 8000 lbs indicated really equated to 6200 lbs actual and the right hand fuselage tank is now empty. It is also possible that this 1800 lbs was inadvertently transferred to other tanks, via broken or leaking valves, rather than being burned. Reference T.O. 1C-130(H)H-1, page 3-23 Warning and page 7-7 Note which states, "Any time the refuel/dump manifold is pressurized for any reason, fuel can transfer into any tank. This is possible due to leakage through a check valve, a malfunctioning refuel shutoff float valve, or loose connections on the fuel line in the tank. When this manifold is pressurized, all fuel quantity indicators must be closely monitored for an unusual change in quantity, or if fuel indicators are inoperative, fuel flow versus fuel quantity and lateral trim must be monitored." At this point, the aircraft is one hour and 24 minutes into the flight--a time when the flight engineer needs to use fuel from the left hand auxiliary tank and the same time when unexplained torque fluctuations occur. If the main tank pumps were turned off and the fuel panel warning/caution lights not seen or believed, then the engines could have flamed out due to pressurized cabin air entering the fuel supply manifold via either the empty left hand or right hand fuselage tank, which worked its way out to all four engines.

 

Time

(minutes)

Fuel Used

(k lbs)

Fuel Source, Duration and Quantity Used
Start, Taxi

15

0.75

Tank-to-Engine, 15 min, 750 lbs
Takeoff

2

0.30

Tank-to-Engine, 2 min 300 lbs
Climb

20

2.35

Tank-to-Engine, 10 min, ~1150 lbs then Right Hand Fuselage, 10 min, ~1200 lbs
Cruise

64

5.00

Right Hand Fuselage, 64 min, 5000 lbs

Table 6-5. Fuel Burn Profile for Scenario Number 2.a

Fuel flow to the engines may have ceased in the following manner:

1. The aircraft either has right hand fuselage tank fuel quantity gauging/indicating problems or leaking/failed fuel valves.

2. All the main tank pumps are off.

3. All the engines are being crossfed from the right hand fuselage tank and it is pumped empty.

4. Illuminated fuel warning/caution lights are either not seen or not believed.

5. Gravity feed does not establish itself from the main tanks.

6. Cabin air enters the fuel supply manifold and is delivered to all four engines.

7. All four engines eventually flameout.

6.4.1.2.2 Scenario Details (Variation B): The second way to run the right hand fuselage tank empty may have occurred as follows. For an unknown reason, the entire sortie, including taxi, takeoff, climb and cruise, were flown while crossfeeding all four engines from the right hand fuselage tank. To fly this profile requires approximately 8400 lbs of fuel, 400 lbs more than that believed to be in the right hand fuselage tank. With fuel quantity gauging/indicating tolerances, it is possible that 8000 lbs indicated really equated to 8400 lbs actual and the right hand fuselage tank is now empty. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the left hand auxiliary tank and the same time when unexplained torque fluctuations occur. If the main tank pumps were turned off and the fuel panel warning/caution lights not seen or believed, then the engines could have flamed out due to pressurized cabin air entering the fuel supply manifold via either the empty left hand or right hand fuselage tank, which worked its way out to all four engines. Fuel flow to the engines may have ceased in the following manner:

1. All the main tank pumps are off.

2. All the engines are being crossfed from the right hand fuselage tank and it is pumped empty.

3. Illuminated fuel warning/caution lights are either not seen or not believed.

4. Gravity feed does not establish itself from the main tanks.

5. Cabin air enters the fuel supply manifold and is delivered to all four engines.

6. All four engines eventually flameout.

6.4.1.2.3 Evidence, Data and Rationale: This scenario (both variations) is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the aircraft’s recent history of fuel gauging problems with some tanks that were being carried as open write-ups, the incidents believed to be caused by fuel starvation that were detailed in Section 5, the incident history and continuing possibility that main tank pumps can be inadvertently left off, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB), and the results of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.2.4 This scenario (both variations) is rebutted by testimony from flight engineers who knew the mishap flight engineer and had never heard him discuss a technique where all the main tank pumps would be turned off. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section. From the recovery videos, this section of the wing contains the crossfeed separation valve and the number 2 main tank crossfeed valve. It probably also contains the number 1 main tank crossfeed valve. These are three of the seven valves that would normally be open if the right hand fuselage tank was crossfeeding to all four engines. Also, the left hand auxiliary tank crossfeed valve, which is part of the wing, should be found closed. The other four valves, the number 3 and number 4 main tank crossfeed valves, the right hand external dump valve and the right hand external tank crossfeed valve are no longer attached to this piece of wreckage. All of these valves are DC powered, and upon the loss of the last engine generator, their positions are captured. Since the cockpit voice recorder is devoid of any discussion of fuel panel actions, the BAR believes that the captured valve positions are the same valve positions as when the power loss first started. The position of these valves will help determine the source of fuel to the engines upon the loss of the last engine generator.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.3 Scenario Number 3. Insufficient Fuel Manifold Priming

6.4.1.3.1 Scenario Details: The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. A switch from the left hand auxiliary tank to the right hand fuselage tank necessitates that the crossfeed manifold, the right external tank manifold, the refuel/dump manifold, and the fuselage tank manifold be primed, or purged of air. According to T.O. 1C-130(H)H-1, page 7-7, priming is required for 30 seconds. Since the crossfeed manifold was successfully used while crossfeeding from the left hand auxiliary tank, it is unlikely it contains any air. However, to get fuel from the right hand fuselage tank also requires the use of three other manifolds. If any of these other manifolds contained significant amounts of air and was not primed sufficiently, remaining air may cause the engines to flameout. Specifically, if the right hand fuselage tank had a failed fuel level control valve that leaked, or two check valves that leaked (all of these items are contained within the fuselage tank), then it is possible to drain, via gravity, much of the fuel in the refuel/dump and fuselage tank manifolds back into the right hand fuselage tank. (This same potential failure mode also exists for the left hand fuselage tank.) As fuel drains from these manifolds, air is allowed to enter into them which must be eliminated via priming. As a final point, it is also worthy to note that with the addition of fuselage tanks to the C-130, it appears that there was no corresponding increase in the time required to prime the longer fuel supply manifold. In short, 30 seconds of priming may be an insufficient amount of priming time. Fuel flow to the engines may have ceased in the following manner:

1. Finished crossfeeding from left hand auxiliary tank.

2. Preparing to use right hand fuselage tank.

3. Manifold not primed sufficiently--air remaining.

4. Significant amount of air routed to all four engines.

5. All four engines eventually flameout.

6.4.1.3.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB), and the results of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). The BAR also spoke to several flight engineers who have experienced torque fluctuations as a result of inadequate priming, including one who had flamed out an engine as a result. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.3.3 This scenario is rebutted by flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB, CA), and by the belief that the flight engineer would surely have made the connection with the transition to a new tank and the engine power loss now occurring. With the connection recognized, it is believed the flight engineer would quickly undo that just done and sought another source of fuel. Additionally, we know from the survivor’s testimony that the flight engineer had been reading a book in the minutes before the power loss occurred. Furthermore, from the cockpit voice recorder, we know the flight engineer was engaged in a discussion with other crew members at the time when the power loss started. All of these factors make it unlikely that improper manifold priming resulted in this mishap. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.4 Scenario Number 4. Right Hand Fuselage Fuel Tank Pump(s) Failure

6.4.1.4.1 Scenario Details: With the preceding fuel load in Table 6-2, it is presumed that the engines fed from their respective main tanks for approximately the first 10 minutes of flight. For the remaining 10 minutes of climb and roughly the next 36 minutes of cruise, it is postulated that the engines were fed fuel from the left hand auxiliary tank. Once the left hand auxiliary tank was emptied, it is presumed that a successful transition to the right hand fuselage tank was accomplished. At one hour and 24 minutes into the flight, it is presumed that the right hand fuselage fuel tank pump(s) failed--the same time when the unexplained torque fluctuations occur. See Table 6-6 for fuel-related details about each phase of the sortie for this scenario. It is also worthy to note that the left hand auxiliary tank may not have been used at all in favor of the right hand fuselage tank during climb and cruise. In this case the right hand fuselage tank would have burned 6200 lbs of fuel when the pump(s) failed.

 

Time

(minutes)

Fuel Used

(k lbs)

Fuel Source, Duration and Quantity Used
Start, Taxi

15

0.75

Tank-to-Engine, 15 min, 750 lbs
Takeoff

2

0.30

Tank-to-Engine, 2 min 300 lbs
Climb

20

2.35

Tank-to-Engine, 10 min, ~1150 lbs then Left Hand Auxiliary, 10 min, ~1200 lbs
Cruise

64

5.00

Left Hand Aux, 36 min, ~2800 lbs then Right Hand Fuselage, 28 min, ~2200 lbs

Table 6-6. Fuel Burn Profile for Scenario Number 4

6.4.1.4.1.1 This scenario presumes that all four engines are being crossfed from the right hand fuselage tank when the pump(s) in that tank fails. Most HC-130P fuselage tanks contain two fuel pumps which can be controlled separately. If only one pump was turned on, which is normal practice, then only one pump must fail to support this scenario. If two pumps were turned on, then both pumps must fail. If the main tank pumps were turned off and the fuel panel warning/caution lights not seen or believed, then the engines could have flamed out due to pressurized cabin air, entering the fuel supply manifold via the empty left hand fuselage tank, which worked its way out to all four engines. Fuel flow to the engines may have ceased in the following manner:

1. All the main tank pumps are off.

2. All the engines are being crossfed from the right hand fuselage tank.

3. The right hand fuselage tank pump(s) fails.

4. Illuminated fuel warning/caution lights are either not seen or not believed.

5. Gravity feed does not establish itself from the main tanks

6. Cabin air enters the fuel supply manifold and is delivered to all four engines.

7. All four engines eventually flameout.

6.4.1.4.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section V, the incident history and continuing possibility that main tank pumps can be inadvertently left off, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB), and the results of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.4.3 This scenario is rebutted by testimony from flight engineers who knew the mishap flight engineer and had never heard him discuss a technique where all the main tank pumps would be turned off. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks. In addition to the items previously addressed for fuselage tanks, the fuel pumps from the right hand fuselage tank are also of interest. It is anticipated that both of these pumps would be examined to help determine if either had failed while operating.

6.4.1.5 Scenario Number 5. Left Hand Auxiliary Fuel Tank Pump Failure

6.4.1.5.1 Scenario Details: This scenario is a variation of scenario number 4. This scenario presumes that all four engines are being crossfed from the left hand auxiliary tank when the pump in that tank fails. To get to this point, a fuel burn similar to that of scenario number 1 could have been used except that the transition to left hand auxiliary tank would have been delayed beyond the 13 minutes after level off cited for scenario number 1. Although the transition could have been accomplished at any time beyond 13 minutes after level off, we have assumed that the transition was made 25 minutes after level off for the sake of discussion. See Table 6-7 for fuel-related details about each phase of the sortie for this scenario. If the main tank pumps were turned off and the fuel panel warning/caution lights not seen or believed, then the engines could have been starved of fuel due to an insufficient fuel flow.

 

Time

(minutes)

Fuel Used

(k lbs)

Fuel Source, Duration and Quantity Used
Start, Taxi

15

0.75

Tank-to-Engine, 15 min, 750 lbs
Takeoff

2

0.30

Tank-to-Engine, 2 min 300 lbs
Climb

20

2.35

Tank-to-Engine, 20 min, 2350 lbs
Cruise

64

5.00

Tank-to-Engine, 25 min, 1950 lbs then Left Hand Auxiliary, 39 min, 3050 lbs

Table 6-7. Fuel Burn Profile for Scenario Number 5

Fuel flow to the engines may have ceased in the following manner:

1. All the main tank pumps are off.

2. All the engines are being crossfed from the left hand auxiliary tank.

3. The left hand auxiliary tank pump fails.

4. Illuminated fuel warning/caution lights are either not seen or not believed.

5. Gravity feed does not establish itself from the main tanks.

6. All four engines eventually flameout.

6.4.1.5.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section 5, the incident history and continuing possibility that main tank pumps can be inadvertently left off.

6.4.1.5.3 The results of ground and flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB) rebuts this scenario. In both cases, when pump failures were simulated in the left hand auxiliary tank, gravity feed successfully established itself. Additionally, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off. See Section 7 or the specific test report document of interest for more details on the results of individual tests. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section. In addition to the items previously addressed, the fuel pump from the left hand auxiliary tank is also of interest. It is anticipated that this pump would be examined to help determine if it failed while operating.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.6 Scenario Number 6. Undetected Fuel Leak

6.4.1.6.1 Scenario Details: This scenario assumes that an undetected fuel leak existed in the refuel/dump manifold. In this scenario, the engines are fed normally from their respective main tanks during takeoff and some portion of climb. The transition to and use of the left hand auxiliary tank is successful. The transition to the right hand fuselage tank is also successful. (Note: The refuel/dump manifold is not pressurized when crossfeeding from the left hand auxiliary tank but is pressurized when crossfeeding from the right hand fuselage tank.) However, at some point, a large fuel leak develops in the refuel/dump manifold outside of the wing (i.e., aft of the aft spar). Unbeknownst to the crew, this leak quickly drains the right hand fuselage tank as well as all four main tanks. With no more fuel on board, all four engines flameout. This scenario assumes that the crew did not notice the problem early because the fuselage tank empty caution light was not seen or burned out. If the crew had noticed this light, they could have come off crossfeed and gone to tank-to-engine without any further problems. Fuel flow to the engines may have ceased in the following manner:

1. Finished crossfeeding from left hand auxiliary tank.

2. Successfully transitioned to right hand fuselage tank.

3. Undetected leak in refuel/dump manifold aft of the aft spar.

4. Right hand fuselage tank emptied.

5. Fuselage tank empty caution light either not seen or burned out.

6. All four main tanks emptied.

7. All four engines eventually flameout.

6.4.1.6.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, and there have been other incidents in the C-130 fleet where minor refuel/dump manifold leaks have gone undetected for a period of time.

6.4.1.6.3 This scenario is rebutted by US Coast Guard and US Navy observations that a large petroleum slick was observed on the ocean’s surface during rescue and recovery efforts. Additionally, US Coast Guard personnel reported that fuel was pouring from the wing during its attempted recovery. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.7 Scenario Number 7. Fuel Dump Valve(s) Stuck Open

6.4.1.7.1 Scenario Details: This scenario is a variation of scenario number 6 and assumes that one or both of the fuel dump valves are stuck open. In this scenario, the engines are fed normally from their respective main tanks during takeoff and some portion of climb. The transition to and use of the left hand auxiliary tank is successful. The transition to the right hand fuselage tank is also successful. However, with the refuel/dump manifold now pressurized, fuel begins to be dumped overboard via one or both dump masts near the wing tips. Unbeknownst to the crew, this uncommanded fuel dumping quickly drains the right hand fuselage tank as well as all four main tanks. With no more fuel on board, all four engines then flameout. This scenario assumes that the crew did not notice the problem early because the fuselage tank empty caution light was not seen or burned out. If the crew had noticed this light, they could have come off crossfeed and gone to tank-to-engine without any further problems. Fuel flow to the engines may have ceased in the following manner:

1. One or both of the fuel dump valves is stuck open.

2. Finished crossfeeding from left hand auxiliary tank.

3. Successfully transitioned to right hand fuselage tank.

4. Right hand fuselage tank emptied.

5. Fuselage tank empty caution light either not seen or burned out.

6. All four main tanks emptied.

7. All four engines eventually flameout.

6.4.1.7.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, and the fact that there have been other incidents in the C-130 fleet where uncommanded dumping has gone undetected for a period of time.

6.4.1.7.3 This scenario is rebutted by US Coast Guard and US Navy observations that a large petroleum slick was observed on the ocean’s surface during rescue and recovery efforts. Additionally, US Coast Guard personnel reported that fuel was pouring from the wing during its attempted recovery. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.8 Scenario Number 8. Refuel/Dump Line Rupture

6.4.1.8.1 Scenario Details: This scenario is the same as scenario number 6 except that the leak is assumed to be much larger. The leak is so large, that when combined with a presumed low pressure area just behind the aft spar, fuel is actually pulled/siphoned from the refuel/dump manifold to such an extent that an insufficient fuel flow is available to the engines and they flameout. This occurs even though there is still a significant amount of fuel remaining in the right hand fuselage tank and main tanks. Fuel flow to the engines may have ceased in the following manner:

1. Finished crossfeeding from left hand auxiliary tank.

2. Successfully transitioned to right hand fuselage tank.

3. Undetected rupture of refuel/dump manifold aft of the aft spar.

4. Fuel is pulled/siphoned from the refuel/dump manifold.

5. Reduced fuel flow causes all four engines to eventually flameout.

6.4.1.8.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow and the fact that engines were lost sequentially not simultaneously.

6.4.1.8.3 Nothing currently rebuts this scenario. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.9 Scenario Number 9. Water in Right Hand Fuselage Fuel Tank

6.4.1.9.1 Scenario Details: Water can be inadvertently introduced into or accumulate in fuselage tanks. The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. Portland had experienced extremely rainy weather in the days prior to the mishap. This rainfall may have worked its way into a fuel servicing vehicle that was dispatched to service the King 56. Or equivalently, several temperature cycles during extremely humid conditions may have resulted in significant condensation inside the fuselage tanks. If this water was not drained from the right hand fuselage tank, it may have been sent to the engines resulting in four flameouts. Currently, there is no requirement to periodically sump fuselage tanks. Fuel flow to the engines may have ceased in the following manner:

1. Water finds its way into the right hand fuselage tank.

2. Right hand fuselage fuel tank is not sumped prior to flight.

3. Finished crossfeeding from left hand auxiliary tank.

4. Successfully transitioned to right hand fuselage tank.

5. Water is sent to all four engines.

6. All four engines eventually flameout.

6.4.1.9.2 Evidence, Data and Rationale: This scenario is corroborated by the fact that engines were lost sequentially not simultaneously, the rainy weather at Portland in the days prior to the mishap, and the fact that no requirement exists to sump (draining at lowest point of the tank to check for and drain water and contaminants) fuselage tanks.

6.4.1.9.3 This scenario is rebutted by the performance of a positive fuel flow check (reference T.O. 1C-130(H)H-1, page 7-5) on the ground which would have identified water in the tank, the crew’s recorded comments pertaining to fuel flow, and the fact that laboratory testing performed on fuel samples taken from the tank farm at Portland, the truck that serviced King 56, the recovered number 4 engine, and recovered aircraft fuel tank foam revealed nothing unusual. Additionally, other aircraft serviced by the same truck used their fuel without incident. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.10 Scenario Number 10. Water in Left Hand Auxiliary Fuel Tank

6.4.1.10.1 Scenario Details: This scenario is a variation of scenario number 9. Water can be inadvertently introduced into or accumulate in auxiliary tanks. Portland had experienced extremely rainy weather in the days prior to the mishap. This rainfall may have worked its way into a fuel servicing vehicle that was dispatched to service King 56. Or equivalently, several temperature cycles during extremely humid conditions may have resulted in significant condensation inside the auxiliary tank. If this water was not drained from the left hand auxiliary tank, it may have been sent to all of the engines resulting in four flameouts. T.O. 1C-130H-2-12JG-10-1, page 1-76 requires sumping of main tanks (only for those not modified by TCT.O. 1C-130-1309 and having a tail number below 73-1580), auxiliary tanks and external tanks. The BAR talked to several flight line personnel at various bases who indicated that this does not routinely occur. Fuel flow to the engines may have ceased in the following manner:

1. Water finds its way to the left hand auxiliary tank.

2. Left hand auxiliary fuel tank is not sumped prior to flight

3. Finished crossfeeding from right hand fuselage tank.

4. Successfully transitioned to left hand auxiliary tank.

5. Water is sent to all four engines.

6. All four engines eventually flameout.

6.4.1.10.2 Evidence, Data and Rationale: This scenario is corroborated by the fact that engines were lost sequentially not simultaneously, the rainy weather at Portland in the days prior to the mishap, and testimony indicating that sumping does not routinely occur.

6.4.1.10.3 This scenario is rebutted by the performance of a positive fuel flow check (reference TO 1C-130(H)H-1, page 7-5) on the ground which would have identified water in the tank, the crew’s recorded comments pertaining to fuel flow, and the fact that laboratory testing performed on fuel samples taken from the tank farm at Portland, the truck that serviced King 56, the recovered number 4 engine, and recovered aircraft fuel tank foam revealed nothing unusual. Additionally, other aircraft serviced by the same truck used their fuel without incident. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.11 Scenario Number 11. Contaminated Fuel

6.4.1.11.1 Scenario Details: Periodically fuel becomes contaminated. This contamination can come from the aircraft or an outside source. Regardless of the source, fine particulate contamination is of concern in this scenario. It is postulated that fine particulates could work their way past the aircraft fuel filters, into the engine fuel controls, and over time, adversely affect the fuel metering valves inside the fuel controls. In certain circumstances, this could lead to engine flameouts. Fuel flow to the engines may have ceased in the following manner:

1. Fine particulate contamination finds its way into the engine fuel controls.

2. The contamination gradually accumulates in the fuel controls.

3. This contamination adversely affects the fuel metering valves.

4. All four engines eventually flameout.

6.4.1.11.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, and there has been at least one other incident in the C-130 fleet where multiple engines have flamed out due to fuel contamination.

6.4.1.11.3 This scenario is rebutted by the fact that laboratory testing performed on fuel samples taken from the tank farm at Portland, the truck that serviced King 56, the recovered number 4 engine, and recovered aircraft fuel tank foam revealed nothing unusual. Physical evidence needed to further corroborate or rebut this scenario are:

1. Additional Engines. The recovery of additional engines may yield more clues about the possible presence of contaminated fuel. The low pressure filter, fuel pumps, fuel control, and temperature datum valve recovered with the number 4 engine are scheduled to be examined in January 1998.

6.4.1.12 Scenario Number 12. Right Hand Fuselage Fuel Tank Manual Isolation Valve Closed

6.4.1.12.1 Scenario Details: The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. The manifold that connects the fuselage tanks to the aircraft incorporates three manual isolation valves. One isolation valve simultaneously isolates both fuselage tanks from the aircraft fuel system. The other two valves only isolate one tank each. Since the left hand fuselage tank was not fueled for the mishap sortie, the left hand manual isolation valve may have been closed thereby isolating it from the aircraft fuel system. However, assuming that the right hand fuselage tank was properly fueled, and that somehow its manual isolation valve was closed either instead of or in addition to the left manual isolation valve, fuselage fuel would be trapped and not be available. Again, if the main tank pumps were off and the fuselage tank empty caution light burned out or not seen, then the engines could have been starved by an insufficient supply of fuel or pressurized cabin air may have entered through the empty left hand fuselage tank. Fuel flow to the engines may have ceased in the following manner:

1. The right hand manual isolation valve is inadvertently closed.

2. All the main tank pumps are off.

3. Finished crossfeeding from left hand auxiliary tank.

4. Unsuccessful transition to right hand fuselage tank.

5. Illuminated fuselage tank empty caution light either not seen or not believed.

6. Gravity feed does not establish itself from the main tanks.

7. Cabin air enters the fuel supply manifold and is delivered to all four engines.

8. All four engines eventually flameout.

6.4.1.12.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section 5, the incident history and continuing possibility that main tank pumps can be inadvertently left off, and the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB). Although not an exact replication of this scenario was tested at Edwards AFB, the potential for pressurized cabin air to enter the fuel supply manifold and the potential to eventually flameout all four engines was demonstrated. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.12.3 This scenario is primarily rebutted by the procedure performed for the usage of fuselage fuel (reference T.O. 1C-130(H)H-1, page 7-7) which incorporates several steps to ensure fuel is available, pressurized by a pump and then properly routed to the engines. If this procedure was performed improperly, it is believed that the flight engineer would surely have made the connection with the transition to a new tank and the engine power loss now occurring. With the connection recognized, it is believed the flight engineer would quickly undo that just done and sought another source of fuel. Additionally, we know from the survivor’s testimony that the flight engineer had been reading a book in the minutes before the power loss occurred. Furthermore, from the cockpit voice recorder, we know that the flight engineer was engaged in a discussion with other crew members at the time when the power loss started. Moreover, fuselage tank manual isolation valves are normally left open even when the tanks are empty. Lastly, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off. All of these factors make it unlikely that a closed manual isolation valve resulted in this mishap. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.13 Scenario Number 13. Cabin Pressurization Procedure

6.4.1.13.1 Scenario Details: This procedure involves using cabin pressure, not fuselage tank pumps, to move fuel from the right hand fuselage tank to the engines. The methodology to perform this procedure is covered in T.O. 1C-130(H)H-1, Section 7. The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. Again, if all the main tank pumps were off, not just a maximum of two allowed by the Section 7 procedure, and the left hand fuselage tank manual isolation valve open, pressurized cabin air would be sent through the fuel supply manifold via the empty left hand fuselage tank. If allowed to persist long enough, this would result in four engine flameouts. Fuel flow to the engines may have ceased in the following manner:

1. All the main tank pumps are off.

2. Finished crossfeeding from left hand auxiliary tank.

3. Unsuccessful transition to right hand fuselage tank.

4. Gravity feed does not establish itself from the main tanks.

5. Cabin air enters the fuel supply manifold and is delivered to all four engines.

6. All four engines eventually flameout.

6.4.1.13.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section V, the incident history and continuing possibility that main tank pumps can be inadvertently left off, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB), and the result of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). Although not an exact replication of this scenario was tested at Edwards AFB, the potential for pressurized cabin air to enter the fuel supply manifold and eventually flameout multiple engines was certainly demonstrated. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.13.3 This scenario is primarily rebutted by the procedure performed for the usage of fuselage fuel (reference T.O. 1C-130(H)H-1, page 7-7) which incorporates several steps to ensure fuel is available, pressurized by cabin air and then properly routed to the engines. If this procedure was performed improperly, it is believed that the flight engineer would surely have made the connection with the transition to a new tank and the engine power loss now occurring. With the connection recognized, it is believed the flight engineer would quickly undo that just done and sought another source of fuel. Additionally, we know from the survivor’s testimony that the flight engineer had been reading a book in the minutes before the power loss occurred. Furthermore, from the cockpit voice recorder, we know that the flight engineer was engaged in a discussion with other crew members at the time when the power loss started. There is absolutely no discussion in the cockpit that the crew is about to perform or is performing this atypical cabin pressurization procedure for moving fuel in a standard environment. Lastly, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off. All of these factors make it unlikely that the use of the cabin pressurization procedure to move fuel resulted in this mishap. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.14 Scenario Number 14. Wrong (i.e., Left Hand) Fuselage Fuel Tank Selected

6.4.1.14.1 Scenario Details. This scenario is a variation of scenario number 13. The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. If the flight engineer inadvertently turned on the left hand fuselage tank pump(s), instead of the right hand fuselage tank pump(s), the main tank pumps were turned off and the fuel panel warning/caution lights not seen or believed, then the engines could have flamed out due to pressurized cabin air entering the fuel supply manifold via the empty left hand fuselage tank. Fuel flow to the engines may have ceased in the following manner:

1. All the main tank pumps are off.

2. Finished crossfeeding from left hand auxiliary tank.

3. Left hand fuselage tank pump selected instead of right hand tank pump.

4. Gravity feed does not establish itself from the main tanks.

5. Cabin air enters the fuel supply manifold and is delivered to all four engines.

6. All four engines eventually flameout.

6.4.1.14.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section V, the incident history and continuing possibility that main tank pumps can be inadvertently left off, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB), and the result of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). Although not an exact replication of this scenario was tested at Edwards AFB, the potential for pressurized cabin air to enter the fuel supply manifold and eventually flameout multiple engines was certainly demonstrated. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.14.3 This scenario is primarily rebutted by the procedure performed for the usage of fuselage fuel (reference T.O. 1C-130(H)H-1, page 7-7) which incorporates several steps to ensure fuel is available, pressurized by a pump and then properly routed to the engines. If this procedure was performed improperly, it is believed that the flight engineer would surely have made the connection with the transition to a new tank and the engine power loss now occurring. With the connection recognized, it is believed the flight engineer would quickly undo that just done and sought another source of fuel. Additionally, we know from the survivor’s testimony that the flight engineer had been reading a book in the minutes before the power loss occurred. Furthermore, from the cockpit voice recorder, we know that the flight engineer was engaged in a discussion with other crew members at the time when the power loss started. Lastly, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off. All of these factors make it unlikely that a closed manual isolation valve resulted in this mishap. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.15 Scenario Number 15. Synchrophaser Failure

6.4.1.15.1 Scenario Details: For this scenario, the synchrophaser is presumed to have a single or multiple failure mechanism which results in four-engine flameout. The C-130 fleet has experienced numerous incidents involving uncommanded engine RPM rollbacks during flight (reference Section 5). These RPM reductions are characterized as momentary in nature, usually lasting only several seconds. Typically all four engines are affected simultaneously, and the maximum amount of RPM lost in the worst case (i.e., internal synchrophaser failure) is approximately four percent. There is some ambiguity as to the magnitude of any power loss because the torque gauges in the cockpit are known to provide erroneous readings when their electrical power source is fluctuating. The cockpit torque gauges are powered by the essential AC bus, the same bus powering the synchrophaser.

6.4.1.15.1.1 Fluctuations in essential AC power, essential bus generator failure, faulty/loose synchrophaser-related wiring, exposure of the synchrophaser to moisture, internal synchrophaser failures, or electromagnetic interference can result in four engine RPM rollbacks. All exact failure mechanisms are not known, but the RPM reductions may occur if the engines are in the normal or synchrophasing mode and erroneous signals reach the speed bias motor. The issue addressed by this scenario is whether this situation can deteriorate to engine flameout. The engines may have flamed out in the following manner:

1. An unknown failure mode adversely affects the synchrophaser.

2. Uncontrollable commands are sent from the synchrophaser to all engines.

3. All four engines eventually flameout.

6.4.1.15.2 Evidence, Data and Rationale: This scenario is corroborated by the history of synchrophaser induced RPM rollback events in the C-130 fleet. However, since none of these events resulted in any engine flameouts, this evidence is not convincing. Additionally, this scenario is corroborated by the aircraft’s history pertaining to electrical system write-ups. This history includes blown fuses, burned out instrument and panel light bulbs, several aircraft battery replacements, a broken electrical wire, and the replacement of two integrated display control units after the morning sortie on 22 Nov 96. Analysis of the "failed" integrated display control units indicates failure may be due to "…temporary periods of poor quality power…"

6.4.1.15.3 This scenario is rebutted by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, and historical ground test results (i.e., Lockheed Report LG88ER0071), and the results of an independently performed failure modes and effects analysis on the synchrophaser. Additionally, analysis of radar information reveals that there is no traffic close to King 56 in the minutes before they experienced problems. This makes it very unlikely that electromagnetic interference from another aircraft was the source of their problem. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.15.4 RPM data obtained from the DFDR reveals steady RPM performance, within the normal operating range, until torque for each respective engine decays to the point where the engine can no longer maintain the propeller at 100% RPM. This is the normal, expected indication of a properly functioning propeller governing system reacting to a decreasing amount of power available from an engine. Additional evidence rebutting this scenario are the electrical and mechanical physical limits placed on synchrophaser control authority which precludes engine flameouts from occurring. The FMECA, when complete, will address multiple failure modes and effects.

6.4.1.15.5 No additional physical evidence is needed to further corroborate or rebut this scenario.

6.4.1.16 Scenario Number 16. Temperature Datum System Failure

6.4.1.16.1 Scenario Details: Each temperature datum system has the ability to take and put fuel to its respective engine. Based upon throttle position, specific fuel properties, and measured engine turbine inlet temperature, each temperature datum amplifier commands its temperature datum valve to take or put fuel to the engine so that targeted turbine inlet temperature is achieved. It is postulated that fluctuations in essential AC and/or DC power, essential bus generator failure, or electromagnetic interference can result in four engine power losses. All exact failure mechanisms are not known, but engine power losses may occur if too much fuel is taken from the engines. In the extreme case, it is presumed that the temperature datum systems might cause engines to flameout. The engines may have flamed out in the following manner:

1. An unknown failure mode adversely affects all temperature datum systems.

2. The temperature datum systems take too much fuel from the engines.

3. All four engines eventually flameout.

6.4.1.16.2 Evidence, Data and Rationale: This scenario is corroborated by the mishap aircraft’s history pertaining to electrical system write-ups. This history includes blown fuses, burned out instrument and panel light bulbs, several aircraft battery replacements, a broken electrical wire, and the replacement of two IDCUs after the morning sortie on 22 Nov 96. Analysis of the "failed" IDCUs indicates failure may be due to "…temporary periods of poor quality power…"

6.4.1.16.3 This scenario is rebutted by historical ground test results (i.e., Lockheed Report LG88ER0071), and the results of ground testing performed at the request of the C-130 BAR (i.e., Allison temperature datum testing at Little Rock AFB). Additionally, analysis of radar information reveals that there is no traffic close to King 56 in the minutes before they experienced problems. This makes it very unlikely that electromagnetic interference from another aircraft was the source of their problem. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.16.4 This scenario is based on the theory that the engine temperature datum amplifiers may react to a low voltage condition in a manner to reduce fuel flow to the engine, causing the engines to flameout. However, there is no DFDR evidence that the aircraft experienced a low voltage condition. To the contrary, the DFDR indicates no apparent voltage anomaly up to the point when the last engine failed and the last generator dropped off the line.

6.4.1.16.5 Two ground tests have been conducted to see if the temperature datum system would react to low voltage and flameout an engine. The first test was conducted by Lockheed, Allison, and Hamilton-Standard in 1988. This laboratory instrumented tests of an engine revealed that the temperature datum system was unaffected by low voltage conditions, and the engine did not flameout.

6.4.1.16.6 Recent tests by the Air Force and Allison showed that a specific model of temperature datum amplifier reduced power output of the engine from 16,000 to 12,000 in-lbs of torque when subjected to a low voltage condition. When the fuel control was maladjusted to a lean fuel schedule and the temperature datum amplifier was subjected to a low AC voltage condition the torque went from 16,000 to 11,500 in-lbs. 11,500 in-lbs of torque is still a significant amount of power. A second temperature datum amplifier model tested did not react to low voltage conditions as in the 1988 test.

6.4.1.16.7 Low voltage conditions did not, in any of the above tests, cause the engine to flameout.

6.4.1.16.8 No additional physical evidence is required.

6.4.1.17 Scenario Number 17. Improper Common Maintenance Action

6.4.1.17.1 Scenario Details: This scenario presumes that there was some common, routine maintenance that was performed on the aircraft that could have adversely affected all four engines. Examples might include a periodic engine filter replacement where filters with too fine a "mesh" were installed. As the aircraft flew, these filters became clogged by particulate matter normally allowed to pass through the proper filters, eventually sufficiently restricting fuel flow leading to engine flameouts. Another scenario may include the installation of the proper filters, but their housings were improperly reassembled leading to nearly simultaneous failure and loss of fuel flow. A final example may include engine oil changes where an inadequate or excessive amount of oil was added to the engines. The engines may have flamed out in the following manner:

1. A maintenance action, common to all four engines, was performed improperly.

2. All four engines, or the systems providing essential functions/material to sustain combustion, are adversely affected.

3. All four engines eventually flameout.

6.4.1.17.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow and the fact that the engines were lost sequentially not simultaneously.

6.4.1.17.3 This scenario is rebutted by the results of the Preflight Inspection performed on 21 Nov 96, the results of the Through Flight Inspection performed on 22 Nov 96, and the recovery of the number 4 engine. The preflight and thru-flight inspections found nothing significant. Additionally, no common maintenance was performed between the morning and evening sorties on 22 Nov 96. The only significant maintenance performed on the aircraft on 22 Nov 96 was the replacement of two IDCUs. Lastly, the number 4 engine, which was recovered and analyzed, revealed no evidence of improper maintenance. Physical evidence needed to further corroborate or rebut this scenario are:

1. Additional Engines.

6.4.1.18 Scenario Number 18. Engine Icing

6.4.1.18.1 Scenario Details: This scenario presumes that icing conditions were encountered which were either not detected or acted upon. This could be due to a failure of either the ice detection or the anti-icing systems. If ice was allowed to build on the aircraft engines, it is postulated that pieces of ice break free, are ingested by the engines, and flame them out. The engines may have flamed out in the following manner:

1. Icing conditions are encountered.

2. The ice detection system fails or the anti-icing system fails.

3. Unbeknownst to the crew, ice forms on engine inlets.

4. Pieces of ice break free and are ingested by the engines.

5. All four engines eventually flameout.

6.4.1.18.2 Evidence, Data and Rationale: This scenario is corroborated by the fact that the engines were lost sequentially not simultaneously, the forecasted weather, and the fact that there have been other incidents in the C-130 fleet where ice ingestion has resulted in engine flameouts. During climb, King 56 was told by Seattle Center to level off at 15,000 feet for crossing traffic. This level off lasted for approximately two minutes. Light icing was forecast for 10,000 to 17,000 feet on departure. It is unknown if the crew activated the engine anti-ice system.

6.4.1.18.3 This scenario is rebutted by the crew’s recorded comments pertaining to fuel flow and the belief that if King 56 experienced icing problems, it would have been while flying at 15,000 feet, not at FL220. FL220 was not forecast for icing. Also, King 56 flew approximately 76 minutes after this very brief encounter with forecast icing at 15,000 feet. Lastly, the number 4 engine, which was recovered and analyzed, revealed no evidence of internal damage due to ice ingestion. Physical evidence needed to further corroborate or rebut this scenario are:

1. Additional Engines.

6.4.1.19 Scenario Number 19. Wrong (i.e., Left Hand) Fuselage Fuel Tank Filled

6.4.1.19.1 Scenario Details: This scenario is a variation of scenario number 14. This scenario assumes that maintenance filled the left hand fuselage tank instead of the right hand one and that all three manual isolation valves are open. The fuel burn for this scenario is assumed to be the same as previously described in scenario number 1. The engines fed from their respective main tanks for approximately the first 33 minutes of flight. This is followed by 51 minutes of all four engines being fed fuel from the left hand auxiliary tank. At this point, the aircraft is one hour and 24 minutes into the flight--the time when the flight engineer needs to use fuel from the right hand fuselage tank and the same time when unexplained torque fluctuations occur. See Table 6-4 for fuel-related details about each phase of the sortie for this scenario. Again, it is presumed the main tank pumps are off and that there is some crossed wiring such that the fuel in the left hand fuselage tank is indicated on the right hand fuselage tank quantity gauge in the cockpit. When the flight engineer intends to crossfeed "fuel" from the right hand fuselage tank in the usual way, pressurized cabin air enters the fuel supply manifold, via the empty left hand fuselage tank, resulting in four engine flameouts. Fuel flow to the engines may have ceased in the following manner:

1. Fuselage tank quantity indicating wiring is somehow crossed.

2. The left hand fuselage tank is filled instead of the right.

3. All the main tank pumps are off.

4. Finished crossfeeding from left hand auxiliary tank.

5. Right hand fuselage tank pump is turned on.

6. Gravity feed does not establish itself from the main tanks.

7. Cabin air enters the fuel supply manifold and is delivered to all four engines.

8. All four engines eventually flameout.

6.4.1.19.2 Evidence, Data and Rationale: This scenario is corroborated by the crew’s recorded comments pertaining to fuel flow, the fact that engines were lost sequentially not simultaneously, the incidents believed to be caused by fuel starvation that were detailed in Section V, the incident history and continuing possibility that main tank pumps can be inadvertently left off, the aircraft’s recent history of fuel gauging problems with some tanks that were being carried as open write-ups, the results of ground testing performed at the request of the BAR (i.e., Allison’s air injection testing at Little Rock AFB) and the results of flight testing performed at the request of the BAR (i.e., Air Force testing at Edwards AFB). Although not an exact replication of this scenario was tested at Edwards AFB, the potential for pressurized cabin air to enter the fuel supply manifold and eventually flameout multiple engines was certainly demonstrated. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.19.3 This scenario is primarily rebutted by the procedure performed for the usage of fuselage fuel (reference T.O. 1C-130(H)H-1, page 7-7) which incorporates several steps to ensure fuel is available, pressurized by a pump and then properly routed to the engines. If this procedure was performed improperly, it is believed that the flight engineer would surely have made the connection with the transition to a new tank and the engine power loss now occurring. With the connection recognized, it is believed the flight engineer would quickly undo that just done and sought another source of fuel. Additionally, we know from the survivor’s testimony that the flight engineer had been reading a book in the minutes before the power loss occurred. Furthermore, from the cockpit voice recorder, we know that the flight engineer was engaged in a discussion with other crew members at the time when the power loss started. Lastly, testimony from flight engineers who knew the mishap flight engineer had never heard him discuss a technique where all the main tank pumps would be turned off. All of these factors make it unlikely that a closed manual isolation valve resulted in this mishap. Physical evidence needed to further corroborate or rebut this scenario are:

1. The Wing Section.

2. The Forward Fuel Control Panel and the Auxiliary Fuel Panel.

3. Both Fuselage Tanks.

6.4.1.20 Scenario Number 20: Synchrophaser and Temperature Datum Failures

6.4.1.20.1 Scenario Details: This scenario is a combination of the synchrophaser failure and temperature datum system failure scenarios detailed separately as scenarios number 15 and number 16. In this case, it is presumed that there is an unknown failure mode such that the combined interaction of both systems reduces both engine RPM and fuel flow in such a manner as to cause all engines to flameout. Another possibility is that the combined effect would reduce RPM to the point of opening of the acceleration bleed valves, reducing compressor efficiency so that the total effect of all events results in engine flameouts. The engines may have flamed out in the following manner:

1. Unknown failure modes adversely effect the synchrophaser and temperature datum systems.

2. Uncontrollable commands are sent from the synchrophaser to all engines at the same time when the temperature datum systems are taking too much fuel from the engines.

3. As the engine RPM drops to 94%, the acceleration bleed valves open.

4. All four engines eventually flameout.

6.4.1.20.2 Evidence, Data and Rationale: This scenario is corroborated by the history of synchrophaser induced RPM rollback events in the C-130 fleet. However, since none of these events resulted in any engine flameouts, this evidence is not convincing. Additionally, this scenario is corroborated by the aircraft’s history pertaining to electrical system write-ups. This history includes blown fuses, burned out instrument and panel light bulbs, several aircraft battery replacements, a broken electrical wire, and the replacement of two IDCUs after the morning sortie on 22 Nov 96. Analysis of the "failed" IDCUs indicates failure may be due to "…temporary periods of poor quality power…" Lastly, the coupling action of two independent systems (i.e., four temperature datum systems and a synchrophaser) appears even more unlikely even though these specific systems receive power from the same AC electrical power source.

6.4.1.20.3 This scenario is rebutted by historical ground test results (i.e., Lockheed Report LG88ER0071), and the results of an independently performed failure modes and effects analysis on the synchrophaser. Additionally, analysis of radar information reveals that there is no traffic close to King 56 in the minutes before they experienced problems. This makes it very unlikely that electromagnetic interference from another aircraft was the source of their problems. See Section 7 or the specific test report document of interest for more details on the results of individual tests.

6.4.1.20.4 RPM data obtained from the DFDR reveals steady performance, within normal operating parameters, until engine torque for each respective engine decays to the point where the propeller governing system can no longer maintain 100% RPM by adjusting propeller blade angle. This is the normal, expected indication of a properly functioning propeller governing system reacting to a decreasing amount of power available from an engine. Additional evidence rebutting this scenario are the electrical and mechanical physical limits placed on synchrophaser control authority which would preclude engine flameouts from occurring. The FMEA states that no single failure modes exist. The FMECA, when complete, will address multiple failure modes and effects. Physical evidence needed to further corroborate or rebut this scenario are:

1. Additional Engines

Table 6-8. Scenario Summaries Quick Reference

 

Scenario # and Name

Required Deficiency

History of Required Deficiency

Component or System Test Results

Aircraft Test Results

Additional Wreckage Desired

1

Left Hand Auxiliary Fuel Tank Run Empty 4 MT Pumps off Some GF not a given, Air is Detrimental Torque Flux, No FOs

2

Right Hand Fuselage Fuel Tank Run Empty 4 MT Pumps off Some GF not a given, Air is Detrimental FOs Occur

3

Insufficient Fuel Manifold Priming Insufficient Prime Some Air is Detrimental Torque Flux, No FOs

4

Right Hand Fuselage Fuel Tank Pump(s) Failure 4 MT Pumps off, RH Fus Pump Failure Some, Some GF not a given, Air is Detrimental FOs Occur and RH Fus Tank Pumps

5

Left Hand Auxiliary Fuel Tank Pump Failure 4 MT Pumps off, LH Aux Pump Failure Some, Some GF not a given, Air is Detrimental No FOs and LH Auxiliary Tank Pump

6

Undetected Fuel Leak Manifold Leak Some Not Planned Not Planned

7

Fuel Dump Valve(s) Stuck Open Failed Dump Valve(s) Some Not Planned Not Planned

8

Refuel/Dump Line Rupture Manifold Rupture None Not Planned Not Planned

9

Water in Right Hand Fuselage Fuel Tank Water in Fuel Unknown Not Planned Not Planned

10

Water in Left Hand Auxiliary Fuel Tank Water in Fuel Unknown Not Planned Not Planned

11

Contaminated Fuel Contam Fuel Some Not Planned Not Planned

12

Right Hand Fuselage Fuel Tank Manual Isolation Valve Closed 4 MT Pumps off Some GF not a given, Air is Detrimental FOs Occur*

13

Cabin Pressurization Procedure 4 MT Pumps off Some GF not a given, Air is Detrimental FOs Occur*

14

Wrong (i.e., LH) Fuselage Fuel Tank Selected 4 MT Pumps off, Wrong Fus Tank Selected Some GF not a given, Air is Detrimental FOs Occur*

15

Synchrophaser Failure Component Failure Some Torque Flux, No FOs Not Planned None

16

Temperature Datum System Failure Component Failure Some Torque Flux, No FOs Not Planned Additional Engines

17

Improper Common Maintenance Action Repeated Error Unknown Not Planned Not Planned Additional Engines

18

Engine Icing 2 System Failures Some Not Planned Not Planned Additional Engines

19

Wrong (i.e., LH) Fuselage Fuel Tank Filled Wiring Prob, 4 MT Pumps off, Wrong Fus Tank Filled Some, Some, Unknown GF not a given, Air is Detrimental FOs Occur*

20

Synchrophaser and Temperature Datum System Failure Multiple Component Failures Unknown Torque Flux, No FOs Not Planned Additional Engines

MT = Main Tank; GF = Gravity Feed; FO = Flameout

* Not specifically tested; conclusion based upon similarity to other flight test configurations and results.

Wing Section, Forward and Auxiliary Fuel Panels, and Both Fuselage Tanks.

6.5 Summary

6.5.1 Because the foregoing discussion covering all the scenarios is extremely lengthy, a consolidated summary is presented in Table 6-8. In addition, a matrix which succinctly summarizes which pieces of evidence and data corroborate or rebut each scenario is also provided as Table 6-9. At the bottom of Table 6-9 is a listing of the wreckage components needed to further corroborate or rebut each of the scenarios. Both tables distill a tremendous amount of information into very concise, quick references. However, all pertinent information is not included in these tables and they are not intended to be substitutes for either the detailed scenarios above or the test reports referenced in them.

6.5.2 For each scenario, the estimated likelihood of occurrence on King 56 is categorized as either likely or not likely. The determination as to whether a scenario is likely or not likely is based upon physical evidence, ground test results, flight test results, analysis and professional judgment. Of the 20 scenarios, 16 are categorized as unlikely to have occurred to King 56. These 16 scenarios lack compelling evidence, historical data, or results from testing for their corroboration. In many cases they depend upon the occurrence of multiple failures and the lack of system redundancy, design safeguards and crew intervention--these are very unlikely dependencies.

6.5.3 The remaining four scenarios are categorized as likely to have occurred. Scenarios categorized as likely are strongly corroborated by evidence, historical data, and the results of testing. Specifically, logical fuel burn profiles have been developed for each of these four scenarios suggesting their timing is possible for King 56, and the results from aircraft testing definitively showed that engine flameouts may be possible or did occur. In contrast to the 16 unlikely scenarios, there is little rebutting evidence, historical data, or results from testing to suggest that one of these four likely scenarios did not occur. Specific scenario categorization is as follows:

LIKELY

1. Left Hand Auxiliary Fuel Tank Run Empty

2. Right Hand Fuselage Fuel Tank Run Empty

3. Insufficient Fuel Manifold Priming

4. Right Hand Fuselage Fuel Tank Pump(s) Failure

NOT LIKELY

5. Left Hand Auxiliary Fuel Tank Pump Failure

6. Undetected Fuel Leak

7. Fuel Dump Valve(s) Stuck Open

8. Refuel/Dump Line Rupture

9. Water in Right Hand Fuselage Fuel Tank

10. Water in Left Hand Auxiliary Fuel Tank

11. Contaminated Fuel

12. Right Hand Fuselage Fuel Tank Manual Isolation Valve Closed

13. Cabin Pressurization Procedure

14. Wrong (i.e., LH) Fuselage Fuel Tank Selected

15. Synchrophaser Failure

16. Temperature Datum System Failure

17. Improper Common Maintenance Action

18. Engine Icing

19. Wrong (i.e., LH) Fuselage Fuel Tank Filled

20. Synchrophaser and Temperature Datum System Failure

6.5.4 Of the four scenarios categorized as likely, all are related to fuel management and the interruption or loss of a constant fuel delivery to the aircraft engines. If allowed to persist, it is believed that engine torque fluctuations, followed by flameouts, would occur--the same things that were recorded by King 56’s DFDR. The best investigative efforts to date, utilizing available physical evidence, ground test results, flight test results, analysis and professional judgment, have only narrowed the focus to four likely scenarios. However, further steps should be taken to further narrow the list of likely scenarios, or add evidence to one of the not likely scenarios to develop one which is most probable. To accomplish this in a timely manner and with a high degree of certainty, the most prudent step is to obtain more King 56 specific information. That is, recover more wreckage from the ocean floor.

6.5.5 Specific items of recovery should include the wing section, the forward and auxiliary fuel panels, and both fuselage tanks. The wing section should be recovered for its fuel valves and the left hand auxiliary tank fuel pump still contained within it. The right hand fuselage tank should be recovered for its fuel quantity gauge and two fuel pumps. The forward and auxiliary fuel panels should be recovered for their fuel quantity gauges.

6.5.6 Wing Section. Wreckage recovery video taken by the US Coast Guard clearly shows the top and bottom of the wing the day that recovery was attempted by the USCGC Buttonwood. Based upon this video, we know that specific valves and a fuel pump are still inside. These valves are DC powered, and upon the loss of the last engine generator, their positions are captured. The pump may show signs of failing in flight. An examination of each of these components will help narrow the focus to one probable scenario. Lastly, from the USCGC Buttonwood’s log and ocean current information, the BAR believes the approximate wing location is 40.15N and 124.56W. Water depth at this location is approximately 5,200 feet.

6.5.7 Fuselage Tanks. Wreckage recovery video taken by the US Navy clearly shows both fuselage tanks. The right hand fuselage tank is of interest because its fuel quantity gauge and fuel pumps will help narrow the focus to one probable scenario. The fuel quantity gauge is AC powered , and upon the loss of the last engine generator, retains its last reading. From the video, it is difficult to distinguish which of the two tanks is the right hand tank making the recovery of both tanks necessary. From the wreckage video, one of the fuselage tanks was co-located with the tail section. This location is identified as approximately 40.08.30N and 125.12.65W in Tab R of the releasable Legal Report. The location of the second tank is less certain, but it is not too far from the first tank. The M/V Laney Chouest recorded views of both tanks on video tape.

6.5.8 Forward and Auxiliary Fuel Panels. The fuel tank quantity gauges from these panels are of interest because they will yield clues about which tanks were used as sources of fuel sent to the engines during the entire sortie. They will also yield clues about how long they were used as fuel sources. In other words, they will validate or disprove each of the possible fuel burn profiles. Like the fuselage tank fuel quantity gauge, these gauges are AC powered, and upon the loss of the last engine generator, retain their last reading. Unfortunately, the location of the forward and auxiliary fuel panels is not certain. The M/V Laney Chouest recorded exterior views of the cockpit portion of the aircraft, but there are not any interior views of the cockpit. Therefore, determining what panels are still present in the cockpit section is currently impossible. As a consequence, recovery and examination of this cockpit section seems appropriate. Additionally, a comprehensive search of the immediate area surrounding this cockpit section is necessary as well since the necessary gauges may have broken free. The specific location of the cockpit section is not known but the M/V Laney Chouest video taped it on 15 Dec 96--the same day it video taped the two fuselage tanks.

6.5.9 It should be noted that although all the fuel quantity gauges work the same way, they are not identical and this will aid in determining a probable scenario even if all the fuel quantity gauges are not recovered still attached to their respective panels. For example, number 1 main tank, number 4 main tank, and both external tank gauges have dial faces which read from zero to 9000 lbs of fuel. Therefore, recovery of just one of these gauges, which indicates other than zero lbs, is necessary to get a good idea of the amount of fuel in each of the four main tanks--presuming all four main tanks were used equally. Both external tank gauges should indicate zero lbs since they were not filled with fuel prior to take off. Of course, recovery of additional main tank gauges only provides a better indication of the fuel load in the main tanks. The number 2 and number 3 main tank gauges have dial faces which read from zero to 8000 lbs; the auxiliary tank gauges have dial faces which read from zero to 6000 lbs; the fuselage tank gauges have dial faces which read from zero to 12,000 lbs; and the totalizer (which does not consider fuselage tank fuel in its reading) reads from zero to 68,000 lbs. Given the indications from several gauges, a complete picture of the fuel load on the aircraft can be established.

6.5.10 Once King 56’s wing, fuselage tanks, and fuel quantity gauges are recovered, the logic tree in Figure 6-10 can be utilized to determine the most probable scenario. The most compelling reason to obtain additional wreckage is the possibility that evidence which supports an unknown new scenario will be found. Recovery of contradictory evidence could indicate that a problem exists within the C-130 fleet.

Table 6-9: Scenario Evidence and Data Quick Reference

EVIDENCE & DATA \ SCENARIO #

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

EVIDENCE
CVR - General Discussions, Fuel Flow Comments

C

C

CR

C

C

C

C

C

R

R

C

CR

CR

CR

R

~

C

R

CR

~

DFDR - Torque, RPM, Seq v. Sim Flameouts

C

C

C

C

C

C

C

C

C

C

C

C

C

C

R

~

C

C

C

R

Aircraft Records

~

C

~

~

~

~

~

~

~

~

~

~

~

~

C

C

R

~

C

C

Weather

~

~

~

~

~

~

~

~

C

C

~

~

~

~

~

~

~

CR

~

~

Radar Data - Departure & End of Sortie

R

~

~

~

~

~

~

~

~

~

~

~

~

~

R

R

~

~

~

R

Fuel Sample Results

~

~

~

~

~

~

~

~

R

R

R

~

~

~

~

~

~

~

~

~

#4 Engine Teardown Results

~

~

~

~

~

~

~

~

~

~

T

~

~

~

~

T

R

R

~

T

HISTORICAL DATA
Previous Main Tank Pump Switch OFF Events

C

C

~

C

C

~

~

~

~

~

~

C

C

C

~

~

~

~

C

~

Other Previous Related Events

~

~

C

~

~

C

C

~

~

~

C

~

~

~

C

~

~

C

~

C

TEST DATA
1988 LM-Allison-HStd Synchro-TD Test

~

~

~

~

~

~

~

~

~

~

~

~

~

~

R

R

~

~

~

R

1997 Allison TD-Low Voltage Test

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

R

~

~

~

~

1997 Allison Air Injection Test

C

C

C

C

~

~

~

~

~

~

~

C

C

C

~

~

~

~

C

~

1997 Edwards AFB Ground Test

C

~

~

~

R

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

1997 Edwards AFB Flight Test

R

C

CR

C

R

~

~

~

~

~

~

C

C

C

~

~

~

~

C

~

1997 Independent Synchrophaser FMEA

~

~

~

~

~

~

~

~

~

~

~

~

~

~

R

~

~

~

~

R

WRECKAGE COMPONENTS \ SCENARIO #

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Floating Wing Section

N

N

N

N

N

N

N

N

N

N

~

N

N

N

~

~

~

~

N

~

Forward & Auxiliary Fuel Panels

N

N

N

N

N

N

N

N

N

N

~

N

N

N

~

~

~

~

N

~

Both Fuselage Tanks

N

N

N

N

N

N

N

N

N

N

~

N

N

N

~

~

~

~

N

~

LH Auxiliary or RH Fuselage Pump(s)

~

~

~

N

N

~

~

~

~

~

~

~

~

~

~

~

~

~

~

~

Additional Engines

~

~

~

~

~

~

~

~

~

~

N

~

~

~

~

~

N

N

~

N

C = Corroborates Scenario
R = Rebuts Scenario
T = To Be Completed
~ = Not Applicable to Scenario
N = Needed to Further Corroborate/Rebut Scenario

Table 6-10: Logic Tree For recovered Wreckage

6.5.11 Related Deficiencies and Concerns

DEFICIENCY: The information in T.O. 1C-130(H)H-1 pertaining to crossfeed operations is inadequate.

RECOMMENDATION: The BAR supports expanding the wording of the flight manual on page 3-24 to more clearly outline the circumstances when air can be introduced into a fuel supply manifold. The wording should provide guidance recommending discontinuing use of an empty crossfed tank after its tank empty light has flickered for a short period of time. It should provide rationale and guidance stating that there is no compelling reason to ever have three or four main tank fuel pumps turned off during flight. The BAR supports amending all affected C-130 T.O.s accordingly.

DEFICIENCY: In the event of a main tank failure, T.O. 1C-130(H)H-1, page 3-23 allows the use of the dump pump from the same main tank to crossfeed to its respective engine. This is an adequate procedure but its use should be discontinued before the dump pump inlet is uncovered. According to T.O. 1C-130(H)H-1, page 1-47, this occurs at approximately 1500 to 2100 lbs, depending upon the specific type of C-130.

RECOMMENDATION: The BAR supports establishment of a fuel quantity limit for use of the above procedure and revising all affected C-130 T.O.s accordingly.

DEFICIENCY: T.O. 1C-130(H)H-1, page 3-24 information pertaining to gravity feed operations requires improvement.

ON-GOING RESOLUTION: The BAR supports amending the T.O. so as to distinguish between establishing gravity feed and sustaining gravity feed. It should clearly define the recommended operating ceiling for gravity feed operations; T.O. 1C-130(H)H-1 implies 30,000 feet whereas Lockheed Report ER-4120 cites 20,000 feet. It should also address the relative probability and length of time required to establish gravity feed from the main tanks when previous flow was from the auxiliary, external and fuselage tanks. Finally, the T.O. should address the sustainment of gravity feed from the main--that is, what to do and what not to do with the aircraft. The BAR supports amending all affected C-130 T.O.s accordingly.

Section 7.0

Test Summaries Pertinent to the King 56 Mishap

7.1 March 1961 Lockheed Report ER-4120; Full Scale Mockup Test of the C-130B Fuel Feed System

7.1.1 Since the C-130B fuel system incorporated significant design changes from the

C-130A, the new system was evaluated. The results of this evaluation are applicable to King 56 because the fuel system of an HC-130P, less its fuselage tank refueling system, is very similar to a C-130B. The C-130B fuel feed system was evaluated on a full-scale laboratory mockup to determine its capabilities and limitations. The fuel system was tested at simulated altitude, with hot fuel, to determine the capabilities of the entire system. A summary of the test results, as quoted from the Lockheed Report, are:

7.1.2 Sea level pressure drop characteristics of the fuel feed system at various flow rates and fuel supply arrangements are presented in this report (meaning the Lockheed Report).

7.1.3 Tests indicate that all engine flow is from the auxiliary tank when the crossfeed system is fed by all tanks (auxiliary, inboard, and outboard) simultaneously.

7.1.4 Tests during which climb-to-altitude on a hot day was simulated, indicated that the engine suction feed system was capable of operating up to altitudes of approximately 20,000 feet with the boost pumps shut off.

7.1.5 Scheduled fuel flow with hot JP-4 and aviation gasoline could be maintained at scheduled rate of climb up to 40,000 feet, with tank boost pumps operating; however, a restricted rate of climb schedule must be maintained with aviation gasoline at a temperature of 110 F or higher in order to limit tank internal pressure.

7.2 April 1988 Lockheed Report LG88ER0071; C-130 Four Engine Power Reduction Test

7.2.1 During the 1980s there were numerous reported power loss events (reference Figure 5-3) which ultimately culminated in power loss testing performed in early 1988. The results of this test effort are documented in Lockheed Report LG88ER0071. Selected paragraphs from the report’s Foreword and Summary are presented below.

7.2.2 Four engine power reductions have been experienced on the C-130 with increased regularity. Investigations of aircraft incidents indicated that approximately 75% of the power reductions were caused by failures in the AC power system essential bus, with the remainder caused by failure in the synchrophasing system.

7.2.3 This test was devised to demonstrate the power reduction, to determine what portion of the engine and propeller controls was being affected when the essential bus would experience failures that caused the voltage to vary over a wide range, and to examine possible solutions that would prevent the power reduction.

7.2.4 The test set up included a single T56-A-15 engine on a test stand which was modified to record all vital data pertaining to the engine and propeller while the engine ran as a master or a slave engine. Tests were run using a tube-type synchrophaser and a solid-state synchrophaser with the capability to vary the voltage individually or simultaneously to the synchrophaser, temperature datum amplifier, and the engine instruments.

7.2.5 The test was conducted on February 24-25 and March 10, 1988, by running a total of 144 separate test cases. The following observations were drawn from the data taken during the tests:

7.2.5.1 The maximum torque loss was 32.4% (5,200 inch-pounds) when the tube-type synchrophaser was used and the voltage was varied from 115 to 50 and back to 115 VAC using a 5-second ramp time.

7.2.5.2 The torque loss using the solid-state synchrophaser was of lesser magnitude. The worst case for the solid-state showed a torque loss of 11.8% (1,600 inch-pounds) when the voltage was varied from 115 to 0 to 115 using a 3-second ramp time. The torque loss was even less, 2.9%, when the voltage was varied the same as the tube-type.

7.2.5.3 The temperature datum system does not contribute to the torque loss when the voltage is varied as low as 30 VAC. However, when the voltage went all the way to 0 VAC, the TD system reverts to the hydromechanical fuel schedule (null) and a torque variation of 9.3% (1,260 inch-pounds) was detected.

7.2.5.4 No torque loss could be induced when the propeller governor control was placed in mechanical governing except as described in No. 3 above.

7.2.5.5 At flight idle power setting (approximately 4,000 inch-pounds), no torque loss was noted with either the tube-type or solid-state synchrophaser.

7.2.5.6 Using the Hamilton Standard time delay relay, the magnitude of the torque reduction was limited to 4.4% with the tube-type synchrophaser.

7.2.5.7 With the constant voltage transformer installed, no torque loss occurred.

7.3 Engine Testing - Conducted at Allison in 1988

7.3.1 The "Rollback" tests conducted in 1988 at Allison, on a highly instrumented test stand, concluded:

1. The synchrophaser is sensitive to voltage variations and can command propeller pitch changes during an electrical power system malfunction.

2. The torquemeters are also sensitive to voltage variations, and are therefore unreliable indicators of actual torque during an electrical power interruption.

3. The TD amplifier system does not contribute to four-engine power fluctuations.

7.4 October 1997 Allison Temperature Datum Low Voltage

7.4.1 Tests were conducted at Little Rock AFB, AR, to see how an engine would react to reductions in voltage to the Temperature Datum Control system (TD Amplifier).

7.4.2 The TD system operates on both Alternating Current (AC 115 Volts, 400HZ), and Direct Current 24-28 Volts DC. Two amplifiers were tested, one manufactured by Raven, one by Allied Signal Bendix. Both were solid state amplifiers, which are the current models used in the fleet.

7.4.3 Summary of Test Results:

1. The Raven TD Amplifier was affected by AC voltage drops. The Power level in the engine went from 16,000 in-lbs, to 12,000 in-lbs, temperature went from 963 C to about 855 C, due to the AC voltage dropping slowly from 115 volts AC, down to approximately 48 volts AC.

2. When the Fuel Control was leaned out 20 C, (a worst case condition), the power level dropped from 16,000 in-lbs to 11,500 in-lbs, and the temperature went from 967 C to 843 C and the RPM dropped from 99.4% to 94.5% RPM when the AC voltage was dropped quickly from 115 volts AC to 48 volts AC. Also, with the engine in this low power condition the DC voltage was dropped, and the Raven TD Amplifier "LOCKED" the system at a low power setting. This is the "worst case condition".

3. The Raven model TD Amp did not react to a DC only voltage drop, engine power, RPM, were unaffected.

4. The Bendix TD Amplifier was not affected by AC or DC voltage drops, and therefore did not affect engine power or RPM.

5. A DC voltage drop eventually puts the TD valve in the "LOCKED" condition, and the engine anti-ice system activates.

7.4.4 Conclusion: Voltage drops in both AC and DC affect the TD system depending on which model TD amplifier is used, and can cause power reduction in the engine. But, this does NOT cause the engine to "Flameout" or quit.

7.5 November 1997 Allison Air Injection Test (Test Stand)

7.5.1 Air was introduced into the fuel supply line for an engine on a test stand at Little Rock AFB. Fuel delivery pressure to the engine was regulated to 25 psi for all tests. The fuel drain was removed from the fuel heater/strainer and replaced with appropriate number 4, or 1/4 inch, fittings so that air could be introduced into the system.

7.5.2 As the supply air pressure was increased from zero to 20 psi, no change in engine operation was noted. As the supply air pressure was increased to 30 psi, fuel flow, TIT, torque and then RPM started to decay. Air pressure was reduced to zero psi and the engine recovered.

7.5.3 Supply air pressure was increased from zero to 26 psi and then held at 26 psi, until the engine stabilized. Fuel flow, TIT, and torque decayed significantly, but not RPM. Air pressure was reduced to zero psi and the engine recovered again.

7.5.4 The fuel flow, torque, and TIT are affected by air induced into the fuel system at pressures as low as one psi above fuel boost pressure.

7.6 November 1997 Edwards AFB Testing

7.6.1 HC-130 fuel starvation testing was accomplished to determine the Allison T56-A-15 turboprop engine response, as installed, to various conditions which could cause inadequate fuel flow and/or introduce air into its fuel supply lines. The specific test objectives were:

7.6.2 Auxiliary Tank Pump Failure -- With the engines under test crossfeeding from the left hand auxiliary tank, and their respective main tank pumps turned OFF, a left hand auxiliary tank pump failure was simulated by turning the left hand auxiliary tank pump OFF.

7.6.3 Auxiliary Tank Empty -- With the engines under test crossfeeding from the left hand auxiliary tank, and their respective main tank pumps turned OFF, the left hand auxiliary tank was run empty.

7.6.4 Fuselage Tank Pump Failure -- With the engines under test crossfeeding from the right hand fuselage tank, and their respective main tank pumps turned OFF, a right hand fuselage tank pump failure was simulated by turning the right hand fuselage tank pump OFF. This test objective was accomplished with the manual isolation valve on the empty left hand fuselage tank both opened and closed.

7.6.5 Fuselage Tank Empty -- With the engines under test crossfeeding from the right hand fuselage tank, and their respective main tank pumps turned OFF, the right hand fuselage tank was run empty.

7.6.6 External Tank Pump Failure -- With the engines under test crossfeeding from an external tank, and their respective main tank pumps turned OFF, an external tank fuel pump failure was simulated by turning the external tank pump OFF.

7.6.7 External Tank Empty -- With the engines under test crossfeeding from an external tank, and their respective main tank pumps turned OFF, the external tank was run empty.

7.6.8 Improper Priming -- With the engines under test crossfeeding from the left hand auxiliary tank, and their respective main tank pumps turned OFF, a transition to crossfeeding from the right hand fuselage tank was performed. The fuel supply manifolds were not primed before transitioning to the right hand fuselage tank.

7.6.9 Improper Priming (Boost pumps ON) -- With the engines under test crossfeeding from the left hand auxiliary tank, and their respective main tank pumps turned ON, a transition to crossfeeding from the right hand fuselage tank was performed. The fuel supply manifolds were not primed before transitioning to the right hand fuselage tank.

7.6.10 Gravity Feed Evaluation -- With the engines under test crossfeeding from the left hand auxiliary tank, and their respective main tank pumps turned OFF, the main tank crossfeed valves for the engines under test are switched from open to closed.

7.6.11 Left Bank Evaluation -- With the three engines under test torque fluctuating below 4000 in-lbs simultaneously, a standard rate left hand turn was initiated. Torque fluctuations were established by a right hand fuselage tank pump failure (with the manual shutoff valve for the left hand fuselage tank open) and a right hand fuselage tank being run empty.

7.6.12 Recovery Procedure Evaluation -- Determine a torque fluctuating and flamed out (caused by fuel starvation) HC-130 engine response to the following recovery procedure: (1) Main tank boost pumps ON, (2) Main tank crossfeed valves closed.

7.6.13 The aircraft DFDR was utilized to capture data during all of the test objectives. To augment this data collection, equipment was added to the test aircraft to record turbine inlet temperatures, fuel flows, and fuel pressures for each of the engines. As a backup, the engine instrument panel was also video taped during ground and flight testing.

7.6.14 Ground and flight testing was accomplished at Edwards AFB between 5 and 24 Nov 97 on HC-130(H)N, 90-2103. Testing followed a build up approach. Ground testing was conducted first beginning with single engine scenarios and progressing through four engine scenarios. Single engine tests were conducted on engine number 1, two-engine tests on number 1 and number 2, and three-engine tests on number 1, number 2, and number 4. A "flameout" was defined as RPM rolling below 94%. In general, the single engine and 2-engine scenarios were allowed to proceed to flameout if they began fluctuating. The 3-engine cases were generally allowed to continue until torque had dropped to 4000 in-lbs on all three engines prior to recovery.

7.6.15 Ground tests were conducted on a level engine-run pad at Edwards AFB (approximately 2300 ft pressure altitude) with engines set at 970 C turbine inlet temperature (970 TIT) which produced approximately 15,000 in-lbs of torque and 1,900 pounds per hour (pph) of fuel flow per engine. Flight tests were conducted at 22,000 ft pressure altitude (PA) with engines set at 970 TIT during straight and level unaccelerated flight except for the left bank evaluation. A left bank evaluation was conducted at 22,000 ft PA with engines set at 910 TIT. All flight tests were conducted with an aircraft differential pressure of approximately 7.4 psi.

7.6.16 No fuel starvation scenarios produced engine flameout on the ground. However, the fuselage and external tank pump failure and tank running empty scenarios caused significant engine power loss and flameouts in flight. The results of both ground and flight test results are summarized in Table 7-1. Following the table are more detailed explanations of the results for each test objective.

Table 7-1: HC-130H(N) S/N 90-2103

HC-130 Fuel Starvation Test Results SUMMARY

GROUND TEST

FLIGHT TEST

Total Number of Engines Tested Total Number of Engines Tested

Objective

1

2

3

4

1

2

3

1. Auxiliary Tank Pump Failure

NR

NR

NR

NR

NR

NR

NR

2. Auxiliary Tank Empty

fx

fx

fx

FX

NR

NR

NR

3. Fuselage Tank Pump Failure

NR

NR

NR

NR

FO

FO

FO

4. Fuselage Tank Empty

NR

NR

NR

NR

FO

FO

FO

5. External Tank Pump Failure

~

~

~

~

FO

FO

FO

6. External Tank Empty

~

~

~

~

FX

FO

FO

7. Improper Priming

NR

NR

FX

FX

fx

FX

NR

8. Improper Priming (BP’s ON)

~

~

~

~

~

~

NR

9. Gravity Feed Evaluation

~

~

~

~

NR

~

~

10. Left Bank Evaluation

Not Conclusive

11. Recovery Procedure Evaluation

All Recovered

NR - No significant engine response fx - Torque fluctuations of 1000-4000 in-lbs

FX - Torque fluctuations greater than 4000 in-lbs FO - Engine(s) flamed out

~ - Not tested

7.6.17 Auxiliary Tank Pump Failure -- The auxiliary tank pump failure scenario did not cause abnormal engine response. The fluctuations which did occur during testing of this objective were small enough to be within normal engine and gauge fluctuation, especially during operation on the ground. The fact that no abnormal engine response occurred indicates that the engines smoothly transitioned from crossfeeding from the left auxiliary tank to gravity feeding from their main tank.

7.6.18 Auxiliary Tank Empty -- The auxiliary tank running empty scenario caused significant torque, TIT, and fuel flow fluctuations on the ground but not in flight. Engine fluctuations from this scenario were greatest on the number 2 engine and grew in magnitude as testing progressed in number of engines during ground and flight test. The duration of engine number 2’s fluctuations lasted approximately 50 seconds during ground test and 30 seconds or less in flight. Engine response was significantly larger on the four engine ground test than the three engine ground test. Since four engine flight tests were not conducted, it is unknown whether this scenario would have produced significant engine power loss or flameout. However, significant engine power loss or flameout from the auxiliary tank running empty may be possible.

7.6.19 Fuselage Tank Pump Failure -- The fuselage tank pump failure scenario caused engine flameouts in flight. During three engine flight tests of the fuselage tank pump failure scenario, engine number 4 experienced torque, TIT, and fuel flow fluctuations first followed by engines number 1 and number 2 within 30 seconds.

7.6.19.1 The fuselage tank pump failure flameouts were unexpected test results, because cabin pressurization was expected to feed the engines with the fuselage tank pump failed. The cause of the flameouts were thought to be pressurized cabin air which entered through the empty left fuselage tank and reached the engines. In order to test this theory, a two engine fuselage tank pump failure scenario was flight tested with the left fuselage tank manual isolation valve CLOSED. Closing the manual isolation valve was expected to isolate the empty tank and block the source of air causing flameout. When the manual isolation valve to the left fuselage tank was CLOSED, the fuselage tank pump failure scenario caused significant engine torque, TIT, and fuel flow fluctuations. The maximum fluctuations observed were approximately 12,000 in-lb of torque, 400 degrees of TIT, and 1,100 pph of fuel flow. These fluctuations lasted for approximately 2 minutes and 30 seconds before the engines recovered to full power crossfeeding from the right fuselage tank with the right fuselage tank boost pump OFF (cabin pressurization acting as a fuel pump). The cause of the significant engine response when the empty fuselage tank’s manual isolation valve is CLOSED is thought to be pressurized cabin air entering through the right fuselage tank’s vent valve.

7.6.19.2 The engines reverted to gravity feed during ground test of this scenario when the aircraft was not pressurized, but the engines did not establish gravity feed in flight. This also supports the theory that pressurized cabin air caused engine flameouts by blocking main tank fuel from gravity feeding.

7.6.20 Fuselage Tank Empty -- The fuselage tank running empty scenario caused engine flameouts in flight. During three engine flight tests of the fuselage tank running empty scenario, engines number 1, number 2, and number 4 experienced near simultaneous torque, TIT, and fuel flow fluctuations. Engine power loss and flameout occurred more quickly than in the fuselage tank pump failure scenarios, since a larger volume of air could enter fuel lines through an empty tank than through the tank vent valve. Again, flameouts may be caused by pressurized cabin air entering the crossfeed manifold from the empty fuselage tank and blocking main tank fuel from gravity feeding.

7.6.21 External Tank Pump Failure -- The external tank pump failure scenario caused engine flameouts in flight. The external tank scenarios were not ground tested because they were added to the test plan after ground test was complete. During three engine flight tests of the external tank pump failure scenario, engine number 2 experienced significant torque, TIT, and fuel flow fluctuations approximately two minutes and 30 seconds before engines number 4 and number 1 followed.

7.6.21.1 The external tank pump failure flameouts were unexpected test results, because the external tanks were expected to act like the auxiliary tanks since both tanks are vented to atmospheric pressure. However, when feeding from the external tanks the crossfeed manifold is connected to the dump manifold through a one way check valve. The dump manifold is connected to the fuselage tanks which are at cabin pressure. Therefore, when feeding from external tanks, pressurized cabin air can force its way to the engines through a one way check valve if the pressure in the crossfeed manifold drops low enough. This theory is supported by the fact that engine inlet pressure slowly rose above atmospheric pressure as the engines experienced power loss leading to flameouts. This indicates that pressurized cabin air was slowly forcing its way into the crossfeed manifold, blocking main tank fuel from gravity feeding and flaming out engines.

7.6.22 External Tank Empty -- The external tank running empty scenario caused engine flameouts in flight. During three engine flight tests of the external tank running empty scenario, engine number 2 experienced significant torque, TIT, and fuel flow fluctuations approximately one minute and 30 seconds before engines number 4 and number 1 followed.

7.6.22.1 The external tank running empty flameouts were unexpected test results, because the external tanks were expected to act like the auxiliary tanks since both tanks are vented to atmospheric pressure. However, when feeding from the external tanks the crossfeed manifold is connected to the dump manifold through a one way check valve. The dump manifold is connected to the fuselage tanks which are at cabin pressure. Therefore, when feeding from external tanks pressurized cabin air can force its way to the engines through a one way check valve if the pressure in the crossfeed manifold drops low enough. This theory is supported by the fact that engine inlet pressure slowly rose above atmospheric pressure as the engines experienced power loss leading to flameout. This indicates that pressurized cabin air was slowly forcing its way into the crossfeed manifold, blocking main tank fuel from gravity feeding and flaming out engines.

7.6.23 Improper Priming -- Improper priming scenarios caused severe but brief engine responses during ground and flight testing. Air introduced into the crossfeed manifold caused large rapid engine power loss (to zero torque) during one and two engine flight tests. Engine fluctuations lasted less than 10 seconds as the engines recovered when pressurized fuel from the fuselage tank boost pump reached the engines. A more operationally representative procedure which introduced air between the fuselage tanks and the right external crossfeed valve did not produce any engine response during three engine flight test.

7.6.24 Improper Priming (Main Tank Boost Pumps On) -- The improper priming with main tank boost pumps ON scenario did not cause any abnormal engine response.

7.6.25 Gravity Feed Evaluation -- The gravity feed evaluation procedure caused no abnormal engine response. The fact that no abnormal engine response occurred indicates that the engines smoothly transitioned from crossfeeding from the auxiliary tank to gravity feeding from their main tank.

7.6.26 Left Bank Evaluation -- Response of torque fluctuating engines to pitch, bank, and normal acceleration was inconclusive.

7.6.27 Recovery Procedure Evaluation -- This objective was tested concurrently with all other test objectives. The recovery procedure was used for every torque fluctuating engine recovery, after the test point success criteria were complete, as part of the test point clean up procedure. In the case of the torque fluctuating engines (4000 in-lbs or less total torque), the main tank boost pumps for the engines under test were turned on and then the engine crossfeed valves were closed. In the case of the inboard flamed out engine (windmilling at 45% RPM), the boost pump was turned on then the crossfeed valve closed. The outboard flamed out engine was recovered as RPM was dropping below 94%. No attempt was made to recover multiple engines with a single main tank boost pump; however, based on the rapid rate that the crossfeed manifold was pressurized and the rapid recovery of the engines, it should be possible to do so.

7.6.27.1 Engines recovered from torque fluctuating conditions within five seconds after their main tank boost pumps were turned ON. When the procedure was conducted on flamed out engines, engine start occurred more slowly. The longest time noted was 20 seconds between main tank boost pump ON and engine number 2 start when engine number 2 was flamed out and rotating at approximately 45% RPM.

7.6.27.2 Overall, 22 successful recoveries of torque fluctuating engines were accomplished in 22 attempts and seven successful recoveries of flamed out engines were accomplished in seven attempts. In every case, the engines recovered to normal operation from any of the fuel starvation scenarios tested when they received positive fuel pressure from their respective main tank boost pump.

7.6.28 From this data, the C-130 BAR concludes that several scenarios involving the failure of pumps in selected crossfed tanks with the main tank pumps OFF, or running selected tanks empty with the main tank pumps OFF have the potential to flameout four engines in flight.

7.7 December 1997 Allison Air Injection Test (Aircraft)

7.7.1 Air was introduced into the fuel supply line for an engine on an aircraft at Little Rock AFB. Fuel was gravity fed from the tank to the engine. The fuel drain was removed from the fuel heater/strainer and replaced with appropriate number 4, or 1/4 inch, fittings so that air could be introduced into the system.

7.7.2 The air pressure was increased from 0 to 3 psi, resulting in engine power fluctuations and minimum performance parameters of 94.5% engine RPM, 700 C TIT, 6,500 in/lbs torque, and 1050 lbs per hour fuel flow.

7.7.3 The fuel flow, torque, TIT, and RPM are affected by air introduced into the fuel system at pressures as low as three psi when fuel is being gravity fed.

7.8 Innovative Technologies Report, Synchrophaser FMEA

7.8.1 A Task Order was awarded to Innovative Technologies Corporation (ITC) under the WR-ALC/LB EASES contract to conduct a rigorous study of critical C-130 aircraft systems to determine what possible failures could lead to the loss of all four engines. Specifically, four systems (Electrical System, Fuel System, Engine Control System, and the Propeller Control System) are to be investigated with emphasis of the HC-130P configuration. In addition, a separate Failure Modes, Effects and Criticality Analysis (FMECA) is to be performed on the Synchrophaser subsystem of the Propeller Control System.

7.8.2 The study will be performed in two phases with a possible third phase. Phase 1 is the effort to scope the overall analysis, conduct a preliminary (quick look) analysis and submit a preliminary FMEA of the synchrophaser subsystem and prepare a detailed project plan. Phase 2 is the performance of a detailed analysis of the four systems to include Failure Modes, Effects and Criticality Analysis, Fault Tree Analysis, Sneak Circuit Analysis, Electromagnetic Interference (EMI) Analysis and simulation to the degree appropriate to determine failures that could cause loss of all four engines. At the end of Phase 2, a detailed report will be prepared and submitted on the systems analyzed to include recommendations on any further analysis required to identify the four engine failure cause(s). A final FMECA on the Synchrophaser sub-system is also to be conducted and submitted. Phase 3 would be comprised of any additional analysis and any other tests required or identified in Phase 2, and the submittal of a final report.

7.8.3 The analysis effort was assigned to members of the ITC team capitalizing upon the expertise of each team member. ITC is the prime contractor performing as the team lead and integrator of the effort. Also, ITC performed the analysis of the Fuel and Electrical Systems. Mercer Engineering Research Center (MERC), a subcontractor to ITC, performed the analysis of the engine control and propeller control systems. During Phase 1, Science Applications International Corporation (SAIC), another ITC sub-contractor, identified special analysis tools to be employed during the Phase 2 analysis.

7.8.4 No single failure was identified in any of the four systems investigated in this preliminary analysis that could result in loss of all four engines other than running out of fuel. This is due to a conscious design approach for all systems to provide redundancy as required to prevent a catastrophic event associated with a single failure. Further analysis will most likely have to consider off-nominal performance and/or multiple failures to find event(s) that could lead to four-engine failure.

Section 8.0

C-130 Fleet Safety Corrective Actions

The team identified a number of corrective actions it felt were necessary to implement its review and appropriate for improving C-130 flight safety overall. Our list of actions follows:

8.1 Complete

8.1.1 Publish a Flight Crew Information File entry (known as the "FCIF," a source of immediate information essential for crews to review before their next flight from home station), reminding flight crews to adhere to flight manual procedures for leaving main tank boost pumps on in flight. The BAR took this action to correct misconceptions the BAR had encountered that there were advantages to operating with them off--there were none under normal operating conditions.

8.1.2 Publish a message telling everyone within the Air Force to report all engine power-loss incidents as at least a "HAP" (High Accident Potential). The BAR implemented this procedure to enable proper tracking of engine power-loss incidents for further analysis as required.

8.1.3 Publish a message reiterating instructions on handling procedures for digital flight data recorders. This was done to improve the chances for gathering critical flight data for analysis in future incidents.

8.1.4 Establish and publish a toll-free number available to all personnel for reporting C-130 engine power-loss incidents. The BAR put this number into operation to gather as much information as possible about prior incidents, and to identify possible scenarios for evaluation.

8.1.5 Publish by message the accepted definitions of the terms "power-loss," "rollback," and "flameout." The BAR did this to establish clarity in discussions involving the BAR.

8.1.6 Conduct tests on the Allison temperature datum system on the engines powering the C-130 fleet.

8.1.7 Publish a critical action "bold face" procedure to address the serious situation of multiple engine power loss/RPM rollback emergencies. Results of BAR initiated flight tests have confirmed the inability of the engines to sustain combustion due to fuel starvation in certain situations. These situations can result in power losses that can be recovered by turning on the main fuel tank boost pumps and closing the crossfeed valves. If no corrective action is taken all four engines may flameout.

8.1.8 C-130 ground and flight tests. These tests reviewed a number of scenarios and attempted to duplicate conditions which might have led to the fuel starvation of the engines on King 56. They looked at variations in operating procedures (i.e., changes in switch positions, boost pump operation, pressurization, etc.), which could have contributed to the incident.

8.1.9 Allison T56A-7B engine aeration tests (with engine on a test stand) at Little Rock Air Force Base. The ground tests showed that fuel flow, torque, TIT, and RPM are affected by air induced into the fuel system at pressures as low as one psi above fuel boost pressure.

8.1.10 Allison T56A-7B engine aeration tests (with aircraft-mounted engine) at Little Rock Air Force Base. The ground tests showed that fuel flow, torque, TIT, and RPM are affected by air introduced into the fuel system at pressures as low as three psi when fuel is being gravity fed.

8.2 In Progress

8.2.1 The C-130 "Tiger Team." This broad, multi-disciplinary study by the AMC staff and representatives from the Air National Guard, Air Force Reserve Command, and the several operating commands, is looking at several aspects of the Air Force’s C-130 fleet, training program, personnel, and their future. The Tiger Team’s report provides recommendations for the future of the C-130 fleet, how it should be based and employed, and what should change in C-130 training and operations in the future.

8.2.2 The C-130 BAR. Completion of this report concludes the work of the review.

8.2.3 C-130 Failure Modes, Effects and Criticality Analysis. The FMECA results are expected in November of 1998 and should provide a detailed summary of those conditions under which the C-130’s engines are most likely to fail, and how those failures might occur and be prevented.

8.2.4 Warner-Robins continue to evaluate Forms 1067 suggesting constant ignition source, reverse current relay rewire, and synchrophaser wiring harness replacement.

8.2.5 Warner-Robins continue to purchase and install a form, fit, and function replacement digital flight data recorder (DFDR) for the C-130, and to appropriately "hot-wire" it from the battery, including a "g-cutoff" switch to discontinue operation after impact.

8.3 Future

8.3.1 The Air Force should review and update the existing lead command operating instruction to:

1. Fully reflect command changes which have occurred since the airlift C-130 fleet transferred from Air Combat Command to Air Mobility Command.

2. More fully define the lead command’s leadership role, its responsibilities (particularly with respect to configuration control), its authority to enforce configuration control, and the accountability of other commands to the lead’s direction.

3. Empower the lead command and properly resource the lead and other user/ supporting commands to enable them to:

a. Update, consolidate and standardize aircraft technical manuals and operating guidance to assure crews have standardized procedures and correct performance data.

4. Do the same for maintenance manuals to assure maintainers have the up-to-date information they need to properly maintain the aircraft.

5. Set and enforce a limit on the number of change pages introduced into a manual before it must be replaced, and require emergency procedure changes to be distributed in printed replacement pages within not more than 72 hours of release to eliminate write-in changes.

8.3.2 The Air Force should consider the Federal Aviation Administration and National Transportation Safety Board guidelines and directives when arriving at a standardized set of digital flight data recorder flight parameters which the Air Force should then incorporate into its existing and planned future weapon systems. This would insure that essential flight data is captured for evaluation in future incidents and accidents. The recommendations made previously by the Defense Science Board should be included as a part of this effort.

8.3.3 Until they are replaced with newer, more capable models of the C-130, the Air Force should reevaluate and more closely monitor the EC-130 Commando Solo II mission. The aircraft have the highest empty gross weights of the fleet, owing to the broadcast equipment they carry. The relative age of the aircraft, the requirement to refuel to near emergency gross weight limits for deployments on operational missions, and the high potential for Radio Frequency Interference (RFI) induced electrical problems, combine to identify this mission as one associated with marked higher risk than others. One specific safety concern the team has is that, despite limited two-engine-out sustained flight capability, crewmembers routinely carry no parachutes. The BAR believes this should also be addressed. The 193rd Special Operations Wing at Harrisburg, Pennsylvania is slated to receive new aircraft eventually, subject to defense budget constraints. Until then, the unit must continue to very carefully balance the performance limitations of its aircraft with the demands of its operating environment. The BAR recommends continued close oversight by the unit’s higher headquarters to make certain this balance is safely maintained.

8.3.4 The Air Force should bring the initial mission qualification and continuation training for crew members under the review and standardization of C-130 formal training to assure that all crew members are taught and evaluated on the same procedures. This will aid in eliminating misconceptions about deviations from these procedures, and will help in quickly spreading the word when a procedure needs to be changed as a result of new information.

8.3.5 The Air Force should bring all initial qualification training students to C-130 formal training for the same reason--standardization of C-130 operating procedures worldwide.

8.3.6 The Air Force should continue the installation of a second pump in the fuselage tanks for these and other similarly equipped aircraft.

8.3.7 The Air Force should establish standardized requirements for aircrews to review ditching and bailout on the first leg of each over-water mission, given the importance of crews maintaining a reasonable level of familiarity with these procedures. As part of this effort, the Air Force should:

1. Conduct an analysis of world-wide ditching events. That data should be used to update and standardize all flight manuals with an accurate discussion of ditching survivability and techniques.

2. Review the information concerning bailout in the flight manuals for consistency between models of the same aircraft, and revalidate the accuracy of the information provided to the crew.

8.3.8 Once officially released by the Air Force, incorporate lessons learned from the King 56 incident into a training video presentation for reference and review by all C-130 crew members. An updated training video would incorporate the lessons learned from King 56, the Colombian ditching, the gunship mishap in Africa, and other ditching events, and would be a valuable training tool.

8.3.9 The Air Force should develop and implement a modification to replace the synchrophaser interface wiring bundles on all C-130 aircraft.

8.3.10 The C-130 SPO should develop and implement a modification which would provide power to the DFDR and CVR during battery only operation.

8.3.11 The BAR recommends renewed Air Force-wide emphasis on fuel sampling as part of standard maintenance operations to help identify the presence of water or other contaminants in the fuel.

8.3.12 The BAR recommends renewed Air Force-wide emphasis on proper testing of the C-130 synchrophaser following reported malfunctions, and on more thorough training for maintenance personnel in the performance of those tests.

8.3.13 The BAR recommends that the Air Force establish a fuel quantity limit for using the dump pump as an alternate source of fuel pressure in the event the main boost pump fails and revision of all affected C-130 T.O.s accordingly.

8.3.14 The BAR supports expanding the wording of the flight manual on page 3-24 to more clearly outline the circumstances when air can be introduced into a fuel supply manifold. The wording should provide guidance recommending discontinuing use of an empty crossfed tank after its tank empty light has flickered for a short period of time. It should provide rationale and guidance stating that there is no compelling reason to ever have three or four main tank fuel pumps turned off during flight. The BAR supports amending all affected C-130 T.O.s accordingly.

Section 9.0

Appendices

9.1 Glossary of Terms

Term Definition

ABCCC Airborne Command, Control, and Communications. A flying battlefield operations command post.
ACC Air Combat Command. The major Air Force Command over attack, fighter, rescue, and bomber aircraft.
Aerial Delivery Combat Air Delivery wherein cargo or paratroopers are dropped by parachute.
AFI Air Force Instruction
AFSOC Air Force Special Operations Command. The major Air Force Command over special air operations (PSYOP, gunship, ABCCC, etc.)
Airland Combat Air Delivery wherein cargo or personnel are delivered by landing at an airfield.
AMC Air Mobility Command. The major Air Force Command over cargo aircraft and airlift operations.
ANG Air National Guard
APU An AC Auxiliary Power Unit
Assault Landing A short field landing (3,500’ or shorter runway).
AWADS Adverse Weather Aerial Delivery System
Bailout Emergency egress of an aircraft via parachute.
BAR Broad Area Review
Bold Face Critical items in the flight manual that must be performed immediately to avoid aggravating an emergency and causing injury or damage. These items must be committed to memory.
CAD Combat Air Delivery - delivering cargo by landing at an airfield (airland) or dropping it by parachute (aerial delivery).
Class A Mishap An accident which results in loss of life, permanent disability, loss of aircraft, or over $1M in damage.
Commando Solo II The name for the Psychological Warfare (PSYOP) Mission flown by one ANG unit.
CRM Cockpit Resource Management. Training which focuses on enhancing crew synergy and coordinating mission accomplishment and handling unusual or emergency situations.
Crossfeed To transfer fuel from any tank by routing the fuel through the crossfeed manifold.
CVR Cockpit Voice Recorder
DFDR Digital Flight Data Recorder - a tape recording system that constantly records some aircraft flight instrument readings.
Ditching An emergency procedure by which an aircrew attempts to land a land-based aircraft on the water.
EMI Electromagnetic Interference
ESU Electrical System Upgrade. The C-130 programmed modification to provide no-break power to the sensitive, critical components.
FAA Federal Aviation Administration
FCF Functional check flight. The test flight done immediately following major aircraft maintenance.
FMEA Failure Modes and Effects Analysis
FMECA Failure Modes, Effects and Criticality Analysis
Fuselage tanks Fuel tanks in the cargo compartment of some C-130 aircraft.
Gravity Feed When fuel flows directly from a tank to its associated engine without the use of fuel tank boost pumps.
GTC Gas Turbine Compressor
IDCU Integrated Display Control Unit
INU Inertial Navigation Unit
ISO Isochronal inspection. A home station maintenance action requiring partial disassembly of the airframe.
LTM Lockheed Technical Manual
Master Engine Engine whose propeller RPM is used as the standard against which all other (slave) engines are synchronized.
NTSB National Transportation Safety Board
NVGs Night Vision Goggles
NVIS Night Vision Imaging System
OJT On-the-job training
PDM Programmed Depot Maintenance. Periodic major preventative maintenance performed on an aircraft at a maintenance depot.
Pogo Draining a small amount of fuel out of aircraft tanks to check for contamination.
PQDR Product Quality Deficiency Report
PSI (or psi) Pounds Per Square Inch
PSYOP (pronounced si-op) Psychological Warfare Operations
Rollback An event in which multiple engines experience a sudden, relatively small, and simultaneous reduction in engine RPM--uncommanded by the crew and with no prior indications of engine problems.
RPM Revolutions Per Minute. In reference to the C-130, 100% engine RPM is 13,820 RPM and 100% propeller RPM is 1020 RPM.
SCNS (pronounced "skins") The self-contained navigation system.
SECAF Secretary of the Air Force
Slave Engine Engine whose propeller blade angle is adjusted, via the synchrophaser, to remain in phase and pitch with the master engine.
SPO System Program Office. The Air Force office which handles life cycle management of a weapon system.
Sump Draining a tank at its lowest point to check for and drain water or any other contaminants.
Tank-to-Engine A fuel management configuration in which each engine is fed by the corresponding fuel tank above it.
T.O. Technical Order - Technical Manuals, which outline operations and maintenance of Air Force aircraft, vehicles, and equipment.
TCTO Time Compliance Technical Order - a Technical Order, which must be complied with in a certain period of time.
TD Temperature Datum System, which is composed primarily of the TD valve and TD amplifier (TD amp).
"NULL" Refers to the condition when the TD Amp sends no signal to the TD valve.
"PUT" Refers to the condition when the TD Amp sends a signal to the TD Valve to add fuel.
"TAKE" Refers to the condition when the TD Amp sends a signal to the TD Valve to restrict some fuel.
TIT Turbine Inlet Temperature
UHF Ultra High Frequency
USAF United States Air Force
VHF Very High Frequency

9.2 Team Members and Advisors

               
               
   

C-130 Broad Area Review Team Members

     
     

Name

Organization

     
   

1

Floyd, Maj Gen Bobby HQ AMC/LG      
   

2

Bair, Mr James HQ AFMC/EN      
   

3

Siegel, Col Gregory WR-ALC/LB      
   

4

Snedeker, Col Mike HQ AMC/XP      
   

5

Kane, Col Bill 908 AW (AFRC)      
   

6

Sandiford, Col Gary AF/ILM      
   

7

Macken, Lt Col Jerry AF/XOOX      
   

8

Stanton, Lt Col Dan AFSC      
   

9

Braden, Lt Col Bill HQ AMC/LGAA      
   

10

Williams, Maj Roger AFSC (HC/MC-130)      
   

11

Lesmerises, Capt Alan SA-ALC/LPEBT      
   

12

Cannon, Capt Mike HQ AMC/LG EXC.      
   

13

Wisener, CMSgt Randy HQ AMC/DOV      
   

14

Love, SMSgt Donald M. 145th AW N.C. ANG      
   

15

Nierescher, TSgt Kevin Patrick, (HC-130 Flight Eng)      
   

16

Babcock, TSgt Gary 182AW IL, ANG      
   

17

Anderson, Mr George NTSB      
   

18

Eubanks, Mr Phil WR-ALC/LBR      
   

19

Jones, Mr Rick WR-ALC/LBR      
   

20

McGregor, Mr Ron AFSC      
   

21

Puckett, Mr Ben WR-ALC /LBR      
               
   

ADVISORS

     
     

Name

Organization

     
   

1

Chappell, Col David W. HQ AMC/JA      
   

2

Leong, Lt Col Linda HQ AMC/PA      
   

3

De Castro, Mr Al LMASC      
   

4

Scheurich, Mr Scott Allison      
   

5

Hack, Mr Bill Hamilton Standard      
   

6

Maternowski, Mr George Hamilton Standard