Staff Sgt. Thomas Feenstra, 28th Aircraft Maintenance Squadron B-1 dedicated crew chief, runs auxiliary power units on a B-1 during the Global Strike Challenge at Ellsworth Air Force Base, S.D., Oct. 1, 2012. Eighteen Airmen selected to represent Ellsworth in the challenge were evaluated on maintenance, building and loading munitions, dress and appearance, specialty knowledge, compliance with technical data, standards and policy, and munitions building operations and handling. (U.S. Air Force photo by Airman 1st Class Kate Thornton-Maurer/Released)