U.S. Air Force aerospace propulsion airmen work on a B-1B Lancer bomber engine. U.S. Air Force aerospace propulsion airmen with the 28th Maintenance Squadron work on a B-1B Lancer bomber engine at Ellsworth Air Force Base, S.D., on Feb. 3, 2010. SHARE: Download: Full Size (0.09 MB) Credit: VIRIN: 973563-X-INQ30-063.jpg Photo Gallery