fredag 6. juli 2012

F-22 problemene ikke løst

Oxygen Problems on F-22 Elude the Air Force’s Fixes

JOINT BASE LANGLEY-EUSTIS, Va. — Capt. Jeff Haney was at 51,000 feet on a night flight above Alaska in November 2010 when the oxygen system in his F-22 Raptor fighter jet shut down, restricting his ability to breathe as he plummeted faster than the speed of sound into the tundra below. His plane burned a crater into the ice, froze 40 feet beneath the surface and was not fully recovered until the spring thaw.
Ian C. Bates for The New York Times
Lt. Colonel Pete Fesler with an F-22 Raptor last week at Joint Base Langley-Eustis in Virginia.                           
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Ian C. Bates for The New York Times
F-22 fighter pilot helmets at Langley Air Force base in Hampton, Virginia.
 
Ian C. Bates for The New York Times
Lt. Col. Jeff Hawkins, right, with Maj. Tom Massa before a test simulating oxygen deprivation.
Captain Haney’s death unnerved the elite community of F-22 pilots, as did a series of episodes over the next 18 months in which an alarming number of them experienced symptoms of hypoxia, or oxygen deprivation. The Air Force grounded the Raptor, the jewel of its fleet, but could not find anything wrong, so it put the jet back in the air — only to have the episodes increase. In May, two seasoned pilots took the extraordinary step of telling CBS News’s “60 Minutes” that they refused to fly the plane.
Last month, a breakthrough seemed to come at last. Investigators believed that a malfunctioning pressure vest was restricting pilots’ breathing and that narrow oxygen hoses were leaking and not delivering enough air. Pilots began flying without the vest, and, buoyed by three months without an episode, Air Force officials told the news media that they might be close to a solution.
But last week, as Air Force officials escorted a reporter and a photographer to the Langley flight line to watch F-22s roaring on and off the runway for an ostensible good-news story, it happened again. A pilot pulled his emergency oxygen handle sometime after landing because of what the Air Force characterized as “discomfort” from intermittent air flow into the pilot’s mask during flight. The Air Force is investigating but so far has said little.

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