Staff Sgt. Luke Keigley, 28th Maintenance Squadron aerospace propulsion journeyman, installs an anti-ice valve onto a B-1B engine at Ellsworth Air Force Base, S.D., Jan. 18, 2012. The anti-ice valve prevents ice build up that can potentially damage the fan blades. (U.S. Air Force photo by Airman Alystria Maurer/Released)