Airman 1st Class Collin Dunn, 28th Logistic Readiness Squadron fuels laboratory technician, prepares to conduct a bottle method test on aircraft fuel in the Fuels Lab at Ellsworth Air Force Base, S.D., March 22, 2012. The test measures levels of water, additives, sediment and particulates in fuel to ensure the fuel is within the required limits. (U.S. Air Force photo by Airman 1st Class Kate Thornton/Released)