Tech. Sgt. Ryan Walker (middle), Senior Airman Ryan Cozza (left) and Airman 1st Class William Becker, 28th Aircraft Maintenance Squadron B-1 bomber crew chiefs, review a technical order during a pre-flight inspection at Ellsworth Air Force Base, S.D., Sept. 10, 2013. Among their vast responsibilities crew chiefs maintain and repair aircraft parts and perform general mechanical work. (U.S. Air Force photo by Airman 1st Class Zachary Hada/Released)