Forum: General F-22A Raptor forum

USAF and NASA officials testify before Congress on F-22 Raptor oxygen systems

http://www.flightglobal.com/news/articl ... ms-376492/

Dave Majumdar Washington DC

Senior US Air Force and NASA officials testified 13 May before Congress on the steps the service is taking to ensure that the Lockheed Martin F-22 Raptor is safe to fly.

The USAF is installing;
1- a redesigned breathing regulator/anti-g (BRAG) valve on the Combat Edge upper pressure garment,
2-a new back-up oxygen system and it is changing the oxygen schedule for the jet's onboard oxygen generation system (OBOGS).

"We've reduced the potential negative effects created by high oxygen concentration levels produced by the OBOGS through cockpit selectable oxygen settings," says Maj Gen Charles Lyon, director of operations at the USAF's Air Combat Command.

The USAF continues to fine tune the F-22's oxygen schedule, he adds.

USAF documents show that a modified oxygen schedule was proposed in 2005, but was rejected by the service. The current work on modifying the oxygen concentration entering the pilot's mask is far more comprehensive than the schedule proposed seven year ago, Lyon says.

....

The F-22 was originally designed with a back-up oxygen system, but that apparatus was deleted as a weight saving measure. At the time, the device was not considered a safety critical item, Martin says.

"In retrospect, that was not an appropriate decision," he says.

The back-up oxygen system weighs only 15lbs and will have no impact upon the performance of the jet when it is installed.

The modified BRAG valve, which will prevent the Combat Edge upper pressure garment from improperly inflating when not under g-loading, will be fielded by the end of 2012.

...Clinton Cragg, principle engineer at the NASA engineering safety center, says that his agency concurs with the USAF's findings that toxin substances are not responsible for the Raptor's problems. But, he notes, the F-22 cockpit has no effective means of filtering out "irritants." Some of those irritants could cause breathing problems, Cragg says.

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