ELLSWORTH AIR FORCE BASE, S.D. -- (Left) Senior Airmen John Parris and Christopher Harris, 28th Civil Engineer Squadron heating, ventilation and air conditioning repair journeymen, attempt to remove a stripped screw from an air conditioning unit, April 12. Airmen Parris and Harris are performing general maintenance on the unit so it can continue to operate efficiently. (U.S. Air Force photo/Airman 1st Class Matthew Flynn)