F-22 Raptor oxygen problems may be worse than previously disclosed

Oxygen problems that have plagued the Air Force’s fleet of F-22 Raptor fighter jets may be worse than previously disclosed, according to new information released by two members of Congress.

F-22 pilots have reported dozens of incidents in which the jet’s systems weren’t feeding them enough oxygen, causing hypoxia-like symptoms in the air. Hypoxia is a condition resulting from a deficiency of oxygen reaching tissues of the body that can cause nausea, headaches, fatigue or even blackouts.

On Thursday, Rep. Adam Kinzinger (R-Ill.) and Sen. Mark R. Warner (D-Va.) released information handed over by the Air Force that said pilots had experienced about 26 incidents of apparent oxygen deprivation per 100,000 flight hours — a rate at least 10 times higher than for any other Air Force aircraft.

“This information confirms that the F-22 program is not running at 100% and that the oxygen-deprivation incident rates are much higher than we were initially told,� said Kinzinger, a former Air National Guard pilot.

The announcement is the latest for the controversial F-22, the world’s most expensive fighter jet, which was made byLockheed Martin Corp.and has never been used in combat since entering service in 2005.

The lawmakers held a teleconference Thursday with reporters in which they disclosed the information. Other findings included an early 2011 aircrew survey that found that “a majority of F-22 pilots surveyed did not feel confident� with the plane’s oxygen system.

The Air Force tried to fix the problem by adding a high-efficiency particulate air filter consisting of activated carbon and charcoal.

But, Kinzinger and Warner said, tests performed by Boeing Co. found that the new filter negatively affected the breathing system for F-22 pilots. Boeing formally recommended discontinuing use of the filters April 2 — a recommendation that was adopted by the Air Force about a month later, they said.

The oxygen malfunctions are suspected of playing a role in at least one fatal accident and led to the grounding of the entire F-22 fleet last year for nearly five months. But even after the grounding was lifted, the Air Force said that investigators could not find a “smoking gun� for the problems and that hypoxia incidents continued to occur.

Last month, Defense Secretary Leon E. Panettarestricted flights of the aircraft because of the ongoing problems.

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