Pentagon green lights Osprey aircraft

[thedrifter]

Pentagon green lights Osprey aircraft


By Pamela Hess
UPI Pentagon Correspondent


WASHINGTON, May 23 (UPI) -- The Pentagon has given a green light to the controversial MV-22 Osprey tilt rotor aircraft, essentially closing debate on the future of the oft-troubled airplane/helicopter hybrid.

"I'm at the point now where I believe we have demonstrated sufficient confidence in the aircraft for safety and reliability that we can continue proceeding forward," said Under Secretary of Defense for Acquisition Pete Aldridge at a press briefing Friday, his final one before he retires from his post.

The aircraft still must pass its operational testing. The decision announced Friday allows the Marine Corps to boost production from 11 per year to 14 or 15.

"There are still a lot of things to do. But I do not see anything that would be a show-stopper in the airplane, that would tell us, 'Terminate the program now, because it's not going to make it,'" he said.

The Pentagon's acquisition chief admitted Friday he was "pretty close" to canceling the $37 billion aircraft program after two crashes in 2000 claimed 23 lives -- the second just days before the Defense Department was set to approve production of the Osprey. A subsequent investigation suggested the aircraft's entire hydraulic system needed to be redesigned, and a major flight test program was undertaken to determine the aircraft's special flight requirements.

"When I looked at the airplane, it was clear we did not have a clue as to ... how this airplane flew," said "There are things that we did not know about this airplane up until this flight test program started."

In April 2000, 19 Marines died during training when the aircraft rolled and went into what is known as vortex ring state ? a situation where the rotors are not getting the lift they need because of their pitch and speed.

In December 2000, four were killed when a hydraulic line ruptured after being chafed by electronics wires bundled nearby. When pilots attempted to reset the aircraft's rotors by pressing a certain button, a software problem caused the rotors to move exactly the opposite of the way the pilots expected.

"The cells were inadequately designed. They did not have sufficient attention paid to the hydraulic line location, chaffing, vibration events, things of that nature. It was clear that we did not understand the aerodynamic phenomena that existed both with the vortex ring state, with slow-speed crosswind interactions with these high-downwash propellers. In fact, the independent study said that the engineering was grossly underestimated, and I think I used that term myself for this airplane," Aldridge said.

Aldridge said repeated test flights have now determined at what point the Osprey is vulnerable to vortex ring state and allowed the military to set new flight parameters to keep pilots and crews safe.

"We have hundreds of test points where we have put the airplane right at the point of where it can go into this vortex ring state," he said. "We know that boundary condition."

Pilots will be limited to a descent rate of 800 feet per minute with a flying speed of less than 40 knots, which will give them a comfortable cushion from which to recover. A new voice warning system and a light switch will warn pilots if they are violating these parameters.

"We know we can fly the airplane at twice that number, twice the sink rate, and much slower, and still not enter vortex ring state," he said.

The Marine Corps, U.S. Special Operations Command and the Air Force plan to buy 458 V-22s. They can carry twice as many passengers twice as far and twice as fast as a conventional helicopter in the airplane configuration, but the rotors can tilt up to allow the aircraft to take off and land vertically like a helicopter.


Sempers,

Roger


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