Staff Sgt. Mark Duque (right), Senior Airman Robert Cozza (middle) and Airman 1st Class William Becker, 28th Aircraft Maintenance Squadron B-1 bomber crew chiefs, conduct pre-flight checks on a B-1 at Ellsworth Air Force Base, S.D., Sept. 10, 2013. During pre-flight inspections, crew chiefs examine the exterior and interior of aircraft for any abnormalities. (U.S. Air Force photo by Airman 1st Class Zachary Hada/Released)