Airman 1st Class Charles McRae, left, and Airman Michael Teems, 362nd Training Squadron F-16 crew chief apprentice course students, service a trainer jet at Sheppard Air Force Base, Texas, Aug. 22, 2018. Servicing the jet includes checking the oil and hydraulic fluid to keep the jet in fighting condition. If left unchecked, certain systems like the landing gear or the jet's drag chute would not work properly. (U.S. Air Force photo by Airman 1st Class Pedro Tenorio)