Staff Sgt. Devin Adair, above, and Airman Kaleb Norman, 361st Training Squadron aerospace propulsion apprentice course students, work on a turbine at Sheppard Air Force Base, Texas, July 11, 2018. Adair and Norman are installing a gearbox into the turbine. The gearbox is an external, but essential part to the turbine's engine. The gearbox drives the turbine and without it the turbine is unfunctional. (U.S. Air Force photo by Airman 1st Class Pedro Tenorio)