U.S. Air Force Airman 1st Class Chris Ruwaldt, Airman 1st Class Matthew Katz and Airman 1st Class Thomas Hill, all 20th Aircraft Maintenance Squadron crew chiefs, place a 370 gallon external fuel tank on a F-16 Fighting Falcon that is preparing to leave for Exercise Green Flag West, Shaw AFB, S.C. Aug. 12, 2011. Green Flag West is an exercise that is held at Nellis Air Force Base, Nev., and takes place ten times a year to prepare aircraft and crews for ground support combat training. (U.S. Air Force photo/Airman 1st Class Tabatha L. Duarte)(Released)