The Pentagon said on Thursday it would resume flights of its F-35 fighter jets, which were grounded a week ago after a crack was discovered in an engine blade during a routine inspection.
The cautionary flight suspension began on Feb. 21 after a 0.6 inch crack was found on a turbine blade of a test aircraft at the Edwards Air Force Base F-35 Integrated Test Facility.
Comprehensive tests on the blade were later conducted at the Pratt & Whitney facility in Middletown, Conn., where prolonged exposure to high levels of heat and other operational stressors were determined to be the cause of the crack, a statement from the F-35 Joint Program Office read.
No additional cracks were found during inspections of the remaining inventory, the statement added.
It was the second time F-35s have been grounded in recent weeks. The Pentagon grounded its 25 F-35B jets, used by the Marine corps, on Jan. 18 after a fuel line detached during a training flight.
The F-35B — one of three varieties used by the U.S. — was cleared to resume testing two weeks ago.
The Defense Department touts the Joint Strike Fighter — its most expensive military hardware program, at roughly $400 billion — its "next-generation strike aircraft weapon systems," offering "cutting-edge technologies to the battlespace of the future."
Military planners envision the F-35 as taking a lead role in so-called "first day of war" operations, eventually replacing a range of workhorse jets, including the F-16, the A-10 and the F/A-18. Current plans call for the U.S. to buy 2,443 aircraft under a contract with Lockheed Martin.
NBC News' Courtney Kube and M. Alex Johnson contributed to this report.
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