Airman 1st Class Levi Booker, a preventative maintenance apprentice assigned to the 28th Logistics Readiness Squadron, checks the pressure during a preventative maintenance inspection at Ellsworth Air Force Base, S.D., Dec. 14, 2016. Preventative maintenance keeps the 15 vehicles ready and serviceable at all times. (U.S. Air Force photo by Airman 1st Class James L. Miller)