From left, Airman 1st Class Ryan Marso, Airman 1st Class Sierra Parker and Airman Anthony Garcia, 362nd Training Squadron KC-135 crew chief apprentice course students, replace safety wires on a KC-135 Stratotanker's boom nozzle at Sheppard Air Force Base, Texas, Sept. 27, 2018. The boom nozzle can be modified for different types of aircraft and take about two hours to change. Afterwards it must be secured with safety wires to ensure it holds together during the mission. (U.S. Air Force photo by Airman 1st Class Pedro Tenorio)