Airmen 1st Class Nicholas Summer (left) and Tyler Carr, and Senior Airman Kymric Walker, 28th Maintenance Squadron aerospace propulsion technicians, inspect a B-1 engine during a preposition spare engine inspection in the propulsion back shop at Ellsworth Air Force Base, S.D., Oct. 17, 2013. Ellsworth’s aerospace propulsion Airmen are responsible for inspecting and performing maintenance on more than 80 B-1 engines. (U.S. Air Force photo by Airman 1st Class Rebecca Imwalle/ Released)