The Pentagon says it has lifted an order that briefly grounded its fleet of F-35 fighter jets.
The Fort Worth, Texas-built Lockheed Martin jets were grounded on Feb. 21. That was after the discovery of a small crack in the turbine blade of an engine in one F-35 at Edwards Air Force Base, Calif.
On Thursday evening the Pentagon said all 51 planes had been cleared to resume flight operations.
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It said prolonged exposure to high levels of heat and other unspecific "stressors" were determined to be the cause of the crack. No additional cracks were found.