Another example of inter-service non-communication.
F-22 problem may be identical to F/A-18 problem identified and fixed by the USN years ago!
Carbon monoxide suspected in F-22 grounding - Air Force News | News from Afghanistan & Iraq - Air Force Times
Carbon monoxide suspected in F-22 grounding
By Dave Majumdar - Staff writer
Posted : Thursday Jul 21, 2011 14:17:42 EDT
The prolonged grounding of the Air Force’s F-22 Raptor fleet may be due to carbon monoxide entering the cockpit via the aircraft’s oxygen system, two sources said.
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Part of the problem may be the procedures used at Elmendorf Air Force Base, Alaska, where most of the known incidents have occurred. Because of the harsh climate, pilots often start their jet engines inside a hangar before taking off. Investigators suspect that exhaust gases are getting trapped in the building and subsequently sucked back into the engines, where they enter the bleed air intakes that supply the OBOGS, sources said.
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If the carbon monoxide is being ingested because the engines are being started in confined spaces, a fix could be as simple as moving the jet outside, Weber said. If the engine must be started inside the hangar, the startup of the oxygen system might be delayed until the jet is out in the open, he said.
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The Navy has had similar problems with the OBOGS on its F/A-18 Hornet, which sucked carbon monoxide into its oxygen system during carrier operations.
Between 2002 and 2009, Hornet aviators suffered 64 reported episodes of hypoxia, including two that killed the pilots, according to the July-August 2010 issue of “Approach,” a Navy Safety Center publication.
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According to Navy documents, “Prolonged exposure to jet engine exhaust while sitting behind another aircraft waiting to take off and operating with low bleed air pressures can result in carbon monoxide (CO) breaking through … into the pilot’s breathing gas.”
The Navy modified the planes’ OBOGS to fix the problem, has had no recent similar incidents, and is not currently investigating the systems, Naval Air Systems Command officials said.