Senior Airman Steven Durr, 28th Maintenance Squadron aerospace propulsion journeyman, inspects fan blades on a B-1B engine at Ellsworth Air Force Base, S.D., Jan. 18, 2012. Airmen in the propulsion back shop use this engine during training to identify different foreign object debris damage that can occur. (U.S. Air Force photo by Airman Alystria Maurer/Released)