Tests find cracks in F-35, Pentagon says

Lockheed Martin Corp.'s F-35 jet developed cracks in testing of the fighter's durability and wasn't sufficiently reliable in training flights last year, the Pentagon's chief tester found. On-ground testing of the Air Force and Marine Corps versions of the fighter revealed "significant findings" of cracks on five occasions in fuselage bulkheads, flanges, stiffeners and engine mounts "that will require mitigation plans and may include redesigning parts and additional weight."

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