V-22 Osprey Program Investigating Accident
By Jefferson Morris/Aerospace Daily & Defense Report
04/06/2006 09:01:33 AM
The Marine Corps' V-22 Osprey tiltrotor program is investigating a March 27 accident in which an Osprey on the ground undergoing a post-maintenance checkout experienced an engine control problem that caused it to become accidentally airborne for a few seconds.

Neither of the pilots was injured in the Class-A mishap, which occurred at Marine Corps Air Station New River in North Carolina. The aircraft fell on its landing gear and its right wing broke off.

The accident is designated Class-A because the damage done will cost more than $1 million to repair. The Marine Corps is inspecting the aircraft, which cost more than $70 million to build, to see if it is salvageable, according to V-22 Program Manager Marine Col. Bill Taylor.

The V-22 fleet is not grounded and officials do not expect the accident to derail the program, despite its history. Two fatal V-22 mishaps in 2000 resulted in a blue ribbon panel investigation and nearly caused the effort to be canceled.

Although the investigation is still under way, the accident appears to be attributable to a problem with the V-22's Full Authority Digital Electronic Control (FADEC) system, which regulates engine performance and fuel flow. The aircraft was undergoing a post-maintenance functional check when a faulty FADEC caused the aircraft to experience an uncommanded engine overspeed.

The flight control system automatically compensated for the overspeed, which is assumed to be more likely to occur in flight, by changing the pitch of the rotor blades to slow them down. This caused the aircraft to become unexpectedly airborne. At this point the aircraft automatically switched to a backup FADEC, but this transition takes approximately 2.5 seconds. Although such an interval would not be a problem if the aircraft was flying at higher altitudes, in this case it was enough for the V-22 to crash back to the ground.

The entire flight lasted an estimated total of 3-3.1 seconds, Taylor told reporters during a briefing at the Navy League's Sea-Air-Space exposition in Washington on April 5. Although some eyewitnesses estimated the aircraft reached an altitude of 20-30 feet, flight data information shows 6 to 7 feet, he said.

Not unique

The particular FADEC system is not unique to the V-22 or its Rolls-Royce engines, Taylor said. "This could have happened to any other legacy platform that has a FADEC system," he said. Rolls-Royce plans to update the FADEC to reduce the lag time during switches to backup systems.

The Marines also are revising training manuals to describe the circumstances in which the overspeed can occur on the ground and include an emergency procedure to deal with it, Taylor said. The program also has updated its simulator training to include this contingency.

'Issued a challenge'

The Marines plan to buy 360 V-22s, and the Special Operations Command plans to purchase 50 CV-22 special operations variants. Total production numbers could be at risk, however, because of a recent decision to trim the program's budget to keep it in line with a recent lifecycle cost estimate by the Pentagon's Cost Analysis Improvement Group (CAIG), which determined that the program was being overfunded.

"We have been issued a challenge," Taylor said. "It's a risky proposition to deliver that same program of record to that [new] budget line." The key to preserving production quantities for less money will be the program's multiyear procurement contract, which Taylor hopes will be in place for fiscal 2008. But even with the multiyear contract in place, other efficiencies will have to be found, he said.

Last year the V-22 program was approved for full-rate production. The Marines expect to deploy it overseas in September 2007, although that schedule could be accelerated by several months, Taylor said.

V-22 inquiry knows what, but not why

By BOB COX
STAR-TELEGRAM STAFF WRITER
A V-22 Osprey hovers at Marine Corps Air Station New River in Jacksonville, N.C. It is still not known why a V-22's engines suddenly powered up, causing the craft to land hard and lose a wing.
 
A V-22 Osprey hovers at Marine Corps Air Station New River in Jacksonville, N.C. It is still not known why a V-22's engines suddenly powered up, causing the craft to land hard and lose a wing.

Marine officials overseeing the V-22 Osprey program say they now understand what happened last week when one of the Bell Helicopter tilt-rotor aircraft was damaged in an accident and have taken steps to prevent a recurrence.

But they're still not sure why it happened.

Marines training to fly the V-22 in combat missions have resumed flying even though the cause of the March 27 accident at a base in North Carolina has not been determined.

James Darcy, a spokesman for the Pentagon office that manages the V-22 program, said Wednesday that investigators have concluded that the two pilots at the controls of the aircraft did nothing to cause the accident.

An official investigation of the accident is under way and could take months.

Darcy said Marine pilots were conducting a routine post-maintenance check of the V-22 when the aircraft's engines suddenly gained power, and the aircraft lifted off the ground and then slammed back down, all within a span of perhaps five or six seconds. The hard landing caused the right wing of the aircraft to snap off where it joined the fuselage. No one was injured.

Officials are studying whether the $70 million aircraft can be repaired and at what cost. The accident has been designated a Class A mishap, meaning that damage will exceed $1 million.

Darcy said the V-22 is designed so that the wing breaks away in a very hard landing, relieving stress, rather than have the entire wing structure collapse and crash into the aircraft cabin.

Darcy said the chain of events began when the aircraft's electronic engine controls suddenly signaled the two turbine engines to dramatically increase power. As the power increased, the aircraft's flight-control computer automatically adjusted the pitch, or angle, of the rotor blades so they were taking a bigger bite of air, lifting the aircraft off the ground.

Even as the pilots attempted to react, backup engine controls sensed the problem and reduced power, and the airplane came down on its landing gear.

Initial reports said the aircraft reached an altitude of nearly 30 feet, but Darcy said that was not the case. "It actually went up about six feet."

Darcy briefed the Star-Telegram on the accident by telephone after the V-22 program manager, Marine Col. Bill Taylor, spoke to reporters in Washington, D.C.

Unknown is why the "full authority digital engine controls" suddenly sent fuel surging into the engines to increase power. Darcy said an engineering investigation will look at computer software, electrical wiring and mechanical parts.

Darcy insisted that an uncommanded power surge was not unusual in helicopters.

But retired Marine helicopter pilot Bill Lawrence of Aledo said he had never experienced such a thing in hundreds of hours flying helicopters with electronic engine controls. Lawrence was assigned to manage the V-22 test program, but he retired before the first, oft-delayed test aircraft was delivered.

"If it's a fairly regular occurrence, why haven't they fixed the [engine controls]?" Lawrence said.

Lawrence said the Marines should ground the V-22s until they know exactly what happened.

Darcy said that the accident has been replicated in a flight simulator, and that V-22 pilots will be trained to recognize the power surge problem and respond by increasing power and gaining altitude until they can gain control of the aircraft and bring it back for a controlled landing.

Engine manufacturer Rolls-Royce has also said it can make changes to the engine-control software that should prevent another accident, Darcy said, a process that will take months for design and testing.

Bob Cox, (817) 390-7723 rcox@star-telegram.com

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