An undisclosed number of F-35s that have been grounded since the crash of an F-35B in December are expected to return to flight within weeks, a source with knowledge of the program's status told Inside Defense . The Dec. 15 mishap at Naval Air Station Joint Reserve Base Forth Worth, TX also prompted engine manufacturer Pratt & Whitney and the F-35 Joint Program Office to pause deliveries of new F135 powerplants. According to a statement from JPO today, engine deliveries...