Staff Sgt. David Martindale, 31st Test and Evaluation Squadron at Edwards Air Force Base, Calif. and an F-35 maintenance student, gets ready to work on a training problem Jul. 19, 2012 at Eglin Air Force Base, Fla. F-35 maintenance training is conducted by the 372nd Training Squadron Detachment 19, part of the 982nd Training Group at Sheppard Air Force Base. (U.S. Air Force photo/Dan Hawkins)