Staff Sgt. Dallas English, 28th Logistics Readiness Squadron fuels laboratory NCO in charge, collects jet fuel during a monthly sample test at Ellsworth Air Force Base, S.D., March 26, 2013. Monthly sample tests verify fuel quality in order to safeguard B-1 engines against contamination and damage. (U.S. Air Force photo by Airman 1st Class Anania Tekurio/Released)