F-22 deliveries halted as US Air Force continues grounding


The US Air Force is no longer receiving newly built F-22 Raptors due to the grounding that has affected the fleet since May 3 over oxygen generator concerns.

The US Air Force Times reports that although Lockheed Martin has almost finished fulfilling the Air Force’s 187 aircraft order, it is unable to perform the required flight testing for each aircraft once it has left the factory at Marietta, Georgia, because of the grounding.

Similarly, government test pilots from the Pentagon’s Defence Contract Management Agency (DCMA) cannot fly the F-22’s acceptance flights for newly delivered aircraft.
“Our final assembly is scheduled through to December. That is still ongoing at Marietta,” said Lockheed spokeswoman Stephanie Stinn. “We delivered aircraft 4181 on June 22, to the Air Force, so they have that as their aircraft. After that aircraft, we can’t do the required acceptance flights.”

Another two aircraft, 4182 and 4183, have been finished but await flight testing. Without operation clearance, deliveries have been suspended until further notice.
“4182 and 4183 were scheduled to deliver in July, but they’re not in a position to do any sort of test flights, so we can’t deliver,” Stinn said. “Maybe early August, but we don’t have a definitive date.”

The US Air Force grounded its entire fleet of 165 F-22 Raptors following a stand down from May 3 after reports of “oxygen system malfunctions,” although the Air Force is looking at all aircraft systems.

There have been nine suspected cases of hypoxia during F-22 operations since mid-2008, and recently there have been 14 recorded OBOGS incidents up until the stand down.

The Raptor is the premier US fighter, with cutting-edge “fifth-generation” features, including shapes, materials and propulsion systems designed to make it appear as small as a swallow on enemy radar screens.

Air Force officials say the onboard oxygen generating system (OBOGS) may have been a factor in the crash of an F-22 in November last year. Captain Jeff Haney was killed when his F-22 crashed into the ground on November 16 during a night training flight with another F-22. Since January, Raptors had been kept at altitudes below 25 000 feet during the ongoing investigation in order to lessen the risk in case the oxygen system did indeed cause the crash. If the OBOGS failed at 25 000 feet pilots would have time to recover to lower altitudes where there is enough oxygen in the atmosphere. This is not the case when the aircraft flies at its 50 000 feet ceiling.

Air Force officials could not say when the aircraft would return to the air.

A week after the F-22s were stood down, Air Force technicians began a parallel investigation of the OBOGS on the A-10, F-15E, F-16, F-35 and T-6 aircraft, as all share similar oxygen equipment. However, these are allowed to fly.

Only some F-22s, crewed by test pilots at Edwards Air Force Base in California, are allowed to fly at the moment as they investigate the problem with the F-22. In the meantime, pilots and ground crew continue to train in simulators and perform ground tasks to stay proficient.