More than six weeks later, the Air Force's F-22 fleet is still grounded, as Flightglobal's Steve Trimble pointed out in a story Thursday, and investigators say they're beginning to look beyond the jets' oxygen systems to try to get to the bottom of their problems. The Air Force knows its Raptor pilots were having breathing issues, but it just isn't sure which exact components might have played a role -- or whether the problems are limited to the F-22 fleet.
Although internally described as the "[onboard oxygen generating system] safety investigation", the probe launched after the 3 May safety stand-down of the F-22A fleet is "not limited" to that particular system, Air Combat Command (ACC) said in emailed responses to questions. "We are still working to pinpoint the exact nature of the problem," the ACC said. "It is premature to definitely link the current issues to the OBOGS system."Air Force officials have not connected the Raptor's oxygen system problems with the November crash of an F-22 up in Alaska, or with the Pentagon's decision not to field F-22s in Libya. In retrospect, DoD's choice to keep the Raptor at home may have been wise, given the potential for an accident if something went wrong on a mission.
The stand-down was originally linked to five reports by F-22 pilots of potential oxygen system malfunctions, including one reported instance when an F-22 scraped treetops on final approach. The pilot could not remember the incident after landing, exhibiting a classic symptom of hypoxia ...
The USAF investigation is also comparing the F-22's life support system with other strike aircraft in its fleet, including the Lockheed F-35A Lightning II, Fairchild Republic A-10, Boeing F-15, Lockheed F-16 and Hawker Beechcraft T-6A, the ACC said. The review is aimed at casting a "broad net for comparison", the command added.