F-22 Raptor “smoking gun” not found

Fleet wide study finds a host of problems in F-22 oxygen generation system that caused earlier grounding.

Air Force leaders still do not know for sure why the F-22 Raptor keeps suffocating its pilots after the service completed a fleet-wide study of its aircraft oxygen generation systems.

Air Force engineers didn’t find a “smoking gun” during the Air Force Scientific Advisory Board’s quick-look study, said Lt. Gen. Herbert “Hawk” Carlisle, the Air Force deputy chief of staff for Operations, Plans and Requirements.  Air Force Secretary Michael Donley ordered the study after the service grounded its F-22 fleet when multiple pilots experienced “hypoxia-like” symptoms in flight.

An F-22 pilot crashed and died in November. An Accident Investigation Board found the fighter jet’s bleed air intakes malfunctioned and Capt. Jeffrey Haney “most likely experienced a sense similar to suffocation.” However, the AIB’s controversial report blamed the pilot, not the aircraft for the crash. The Defense Department’s Inspector General is completing an assessment of that report.

Air Force Scientific Advisory Board found that a “couple of contributing factors” to include a leaky cooling system has restricting oxygen reaching pilots, Carlisle said on Tuesday. He didn’t want to list it as the “smoking gun” because service engineers do not know for sure how the fluid from the cooling system got into the F-22’s On Board Oxygen Generating System (OBOGS).

Engineers also found problems with the F-22’s breathing regulator/anti-G valve, better known as the BRAG valve, Carlisle said. The BRAG valve connects the OBOGS to the pilot’s oxygen mask.

When there is a problem, F-22 pilots also do not receive “indications and warnings” fast enough in “fleeting cases”, Carlisle said.

The Air Force three-star said the problems with the oxygen system do not just affect the F-22. Engineers found similar problems in the Navy’s F-18. The Air Force has shared results of their quick look study with Navy leaders.

The quick-look study inspected the oxygen generation systems of the A-10 Thunderbolt II, F-15E Strike Eagle, F-16 Fighting Falcon, F-35 Joint Strike Fighter, B-1 Lancer, B-2 Spirit, CV-22 Osprey, and T-6 Texan II as well as the F-22.

Air Force officials will inspect the F-22’s emergency oxygen system analyzing how it’s used and what “it takes to deploy it,” Carlisle said.

The service will continue to study each case in which F-22 pilots experience hypoxia-like symptoms. A special team continues to inspect the problem, Carlisle said.