F-35 Blade Inspections Haven’t Turned Up More Cracks

The Pentagon’s F-35 program office hasn’t discovered additional engine blade cracks in its fleet of test and operational jets so far, a spokeswoman said.

The Pentagon said Feb. 22 that it suspended all flights of Lockheed Martin Corp.’s F-35 after a routine engine inspection revealed a crack on a turbine blade in a test aircraft engine at Edwards Air Force Base in California.

The entire test fleet -- 17 aircraft based in Maryland and California -- has been inspected and no additional cracks have been discovered, said F-35 program spokeswoman Kyra Hawn. These planes are the flown the hardest, pushed by pilots to the most stressing flight profiles.

The 34 operational aircraft used in pilot and tactics training in Florida and Arizona are still being inspected, Hawn said in an e-mailed statement.

The blade in question was in an engine made by United Technologies Corp.’s Pratt & Whitney unit that was “subjected to more flight hours and wear than aircraft of comparable age,” Hawn said. “It has operated at the extremes of engine temperature and tolerances.”

Pratt & Whitney has completed vibration, air flow and X-ray examinations on the cracked blade, she said. So-called destructive tests designed to examine the blade’s surfaces started today, she said. All test and inspection data should be completed, analyzed and presented no later than March 1, Hawn said.

The Marine Corps version of the F-35 was grounded last month after a pilot aborted a takeoff because of an unrelated flaw in the Pratt & Whitney propulsion system. Those planes resumed flying this month after the problem was traced to an improperly crimped fluid hose.

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