Senior Airman Richard Johnson, crew chief, checks the engine turbines of a KC-10 Extender on April 14, 2011, at a non-disclosed base in Western Europe. Johnson was deployed with the 313th Air Expeditionary Wing from the 349th Air Mobility Wing of Travis Air Force Base, Calif. in support of Operation Unified Protector. Operation Unified Protector was a NATO-led mission in Libya, to protect civilians and civilian-populated areas under threat of attack. The 313th AEW provides aerial refueling to U.S. and coalition aircraft with KC-135 Stratotankers and KC-10s. (U.S. Air Force photo/Senior Airman Ethan Morgan)