Bleed-Air problem caused F-22 crash
The November 2010 crash of a U.S. Air Force F-22 was caused by a malfunction with the aircraft engine’s bleed air system, an industry source said. The pilot, Capt. Jeff “Bong” Haney of the 525th Fighter Squadron, was killed in the accident. An Air Force accident report said the F-22, tail number 06-4125, had a bleed air problem that caused both the stealth fighter jet’s Environmental Control System (ECS) and On-Board Oxygen Generating System (OBOGS) to automatically shut down, the sources said.
The report has been released to Air Force officials at Pacific Air Forces, but has not been made public, the industry source said. The F-22 fleet was grounded May 3 after pilots suffered more than a dozen hypoxia-like incidents while flying.
Lt. Col. John Dorrian, an Air Force spokesman wrote in an email, “The information provided by your ‘industry source’ is not a wholly accurate characterization of the crash. However, due to the ongoing Accident Investigation Board process I am not able to provide point-by-point confirmation, as the information is not yet releasable. PACAF is conducting the AIB process and will release appropriate information once the process is complete.”
The bleed air system siphons off air from a jet engine’s compressor section to generate power, supply oxygen and inert gases, and handle heating and cooling. If the ECS and OBOGS shut down, the pilot would not have air coming into the cockpit, and would have to switch to his emergency oxygen supply and dive to 10,000 feet, another source said.
“If the ECS is out … there is no conditioned air pressure pushing through the OBOGS, so he would be sucking rubber,” the source said. However, as the aircraft descended, “the cabin pressure would be gradually rising as long as the canopy was still intact completely,” he said. But Haney’s F-22 never recovered from its dive. The twin-engine jet hit the ground, and it is unclear whether the pilot had switched to his emergency oxygen supply, the industry source said.
“The rate at which he descended, though, he would have been at a hypoxia-safe altitude within time to have not fully succumbed to hypoxia and should have only had symptoms versus unconsciousness,” the pilot source said. “The green ring [emergency oxygen bottle] in the Raptor is a tough pull, and it was altered to give the pilot some pressure.” Activating the emergency oxygen system is tricky in the Raptor, the source continued.
“It is a double pull that has to be practiced and experienced a few times before you end up in that bad situation, or you will panic,” he said.
The industry source said the report declared that the accident was not related to the OBOGS.
