Cpl. Chris Kelly, Royal Australian Air Force 36th Squadron aircraft technician, tightens a screw on a C-17 Globemaster III aircraft auxiliary power unit April 19, 2016, at Joint Base Lewis-McChord, Wash. More than 40 Australian Airmen attend McChord’s C-17 maintenance course annually. (U.S. Air Force photo/Senior Airman Jacob Jimenez)