F-35 program officials cleared the last three Joint Strike Fighter aircraft to resume flying in early March, two days after the rest of the fleet had its stand-down lifted, and are putting in place a process to ensure engine blade cracks do not occur in the future. The entire JSF fleet was grounded on Feb. 21 after a crack was discovered on an F-35A conventional-takeoff-and-landing jet’s third-stage engine turbine blade. The grounding was lifted for most of the fleet on...