A drop in cockpit oxygen that caused a Hawaii-based F-22 Raptor pilot to feel dizzy during a training flight earlier this month has been deemed a mechanical malfunction and is not related to a string of oxygen deprivation incidents in the spring of 2011, the Air Combat Command said.
The recent onboard oxygen generating system failure also is not specific to the F-22 aircraft, according to the command, based in Langley, Va. The July 6 incident was the first time a Hawaii-based pilot experienced air supply troubles similar to those experienced by many pilots last year.
A Hawaii Air Guard pilot was returning to Joint Base Pearl Harbor-Hickam following a routine training sortie when a cockpit warning alerted him that the onboard oxygen generating system was underperforming, Lt. Col. Chuck Anthony, a Hawaii National Guard spokesman, said last week.
The pilot activated his emergency oxygen system, and his dizziness quickly subsided, Anthony said. The onboard oxygen system also went back into working order before he landed.
The Air Combat Command is conducting a safety investigation, and the aircraft has not yet been returned to service, a command spokesman said Friday by email.
"More details will be available when the investigation is complete, but we’re confident the annunciation of the (onboard oxygen generating system) warning during the flight points to the cause, which was a malfunction within the (onboard oxygen generating system)," the email stated.
The Air Combat Command is the primary provider of combat air forces to America’s unified combatant commands, such as the Hawaii-based Pacific Command.
A pilot out of Langley also experienced in-flight life support system malfunction during a training sortie on June 26.
An Air Combat Command investigation discovered cockpit audio that registered the sounds of a stuck valve at various times during the flight, and oxygen flow became abnormal near the end of the sortie.
Maintenance crews removed and replaced the Breathing Regulator Anti-G valve, pilot breathing hoses, the Emergency Oxygen System Regulator and the Emergency Oxygen System shutoff valve, and that aircraft has returned to flight status, the command said.
An F-22 life support system task force has been investigating a string of incidents that led to a four-month grounding of all F-22 aircraft last year. The Hawaii and Virginia incidents, however, are being classified by Air Combat Command as "of known cause."
As of July 2, 36 life support system failures have been reported, and 21 were classified as unexplained, according to The New York Times.
F-22 Raptors are also housed at four other Air Force bases around the country: Joint Base Elmendorf-Richardson in Alaska, Nellis Air Force Base in Nevada, Holloman Air Force Base in New Mexico and Tyndall Air Force Base in Florida.
