F-35 Tests Suspended After Airborne Glitch - dual generator failure and oil leak

Flight testing of F-35 Lightning II Joint Strike Fighters has been suspended after a U.S. Air Force aircraft experienced a dual generator failure and oil leak during a test sortie on March 9, prime contractor Lockheed Martin said March 11.

THE MARCH 9 incident occurred at Edwards Air Force Base, Calif., which is the main Air Force flight test facility, on aircraft AF-4, pictured above. (Liz Kaszynski / Lockheed Martin)

The plane, an F-35A, returned safely to base, but further test flights are being delayed while engineers figure out the cause of the problem.

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"As a routine safety precaution, the Joint Program Office (JPO) has temporarily suspended F-35 flight operations until a team of JPO and [Lockheed] technical experts determines the root cause of the generator failure and oil leak. Once the cause is known, the appropriate repairs and improvements will be made before flight operations resume," Lockheed spokesman John Kent said in an e-mail.

Unlike previous fighter jets, the F-35's flight control surfaces are moved by electro-hydrostatic actuators powered by electricity. As such, an electrical failure could be especially problematic.

The incident occurred at Edwards Air Force Base, Calif., which is the main Air Force flight test facility, on aircraft AF-4, the fourth Air Force test plane. There are 10 F-35 test aircraft operating at Edwards and Naval Air Station Patuxent River, Md.