The Joint Strike Fighter availability rate holds at a steady 50 percent, but a new report from the Pentagon's top weapons tester reveals an increase in the number of jets that cannot fly because maintenance personnel are awaiting replacement parts. The director of operational test and evaluation report echoes similar concerns cited by the Government Accountability Office in October. The GAO highlighted parts reliability as a major hurdle facing the program. Since October 2014 the overall F-35 fleet-wide monthly availability...