Staff Sgt. Andrew Purshock, 362nd Training Squadron F-16 crew chief apprentice course instructor, explains to his students how to bleed the hydraulics system at Sheppard Air Force Base, Texas, Nov. 14, 2018. Purshock will show his students what each crank does and what the gauges mean and then let his students follow the steps all on their own. Not only will the machine be very loud, but it will also be extremely hot during the bleeding process, so the students must be sure of what they are doing to avoid any injury. (U.S. Air Force photo by Airman 1st Class Pedro Tenorio)