glitch led to fatal Osprey crash
By Sandra Jontz, Washington bureau
WASHINGTON A hydraulics problem one U.S. Marine Corps officials have known about and a glitch in a computer software program led to the December crash of the troubled V-22 Osprey that killed four North Carolina Marines, according to the completed investigation.
One of the three hydraulic lines supplying the tilt-rotor aircraft was chaffed and ruptured under pressure during a nighttime training exercise at New River, N.C., the home squadron of the Osprey, Maj. Gen. Martin Berndt, commanding general of the Second Marine Expeditionary Force at Camp Lejeune, N.C., said Thursday.
The hydraulic lines and wire bundles that supply power to the engines of the aircraft showed signs of wear-and-tear, damage consistent with reports of other hydraulic line problems dating back to June 1999, Berndt said.
When the line ruptured, a computer program signaled the pilot to press the Primary Flight Control System reset button.
Pushing the reset button which the pilot did about eight to 10 times caused the aircraft to uncontrollably accelerate and decelerate, to "pitch, roll and yaw," and eventually stalled the aircraft mid-flight, he said.
Within 30 seconds of the ruptured line, the Osprey crashed nose down in a area 7 miles from the airfield, Berndt said.
"The aircrew reacted immediately and correctly to the in-flight emergency, as they were trained to do," Berndt said. "We consider them to be without fault in this tragedy."
Though investigators had reports citing previous problems with the hydraulic system, there had never been any indication before the December crash that the computer software would malfunction, Berndt said.
The investigators recommended a review of the computer flight control system and the placement of hydraulic lines and wire bundles, he said.
The Osprey has been grounded since the incident, and the Marine Corps is waiting on independent studies by a panel set up by former Defense Secretary William Cohen and the Pentagon inspector general before deciding whether to fly again, Berndt said.
Part of the Inspector Generals investigation focuses on the falsification of maintenance records, allegedly ordered by the squadrons commanding officer.
Marine Corps officials insisted in the past that the allegations did not contribute to the crash.
Thursday, Berndt said the New River Osprey that crashed, referred to as "Crossbow 08," was ahead of its maintenance schedule.
The crash also halted full-rate production progress of the $40 billion program of the unique aircraft that flies both like a helicopter and an airplane. The Marine Corps wants to buy 360 aircraft.
Despite the crashes, Commandant James Jones continues to voice support for the aircraft.
Though the nighttime flying currency for co-pilot Lt. Col. Keith Sweaney had technically expired, it did not contribute to the crash, Berndt said. And there is no documentation that Sweaney nor pilot Lt. Col. Mike Murphy had completed their required monthly emergency procedure exams. That too did not contribute to the mishap, he said.
Last year, 23 Marines were killed in Osprey crashes. A crash a year ago this month ago killed 19 airmen in Arizona.
Naval Air Systems Command will conducted a complete review of the computer software program, and both NAVAIR and Bell-Boeing Co., the aircrafts manufacturer, will review the hydraulic line problem, Berndt said.
Bell-Boeing might have to redesign the hydraulic system to prevent future failures, he said.