Airman 1st Class Alexander Mantha, 364th Training Squadron electrical and environmental apprentice course student, installs a final stage bleed air valve used to regulate air pressure from the engine to the environmental system on an F-15 Eagle at Sheppard Air Force Base, Texas, Jan. 17, 2018. Mantha is in block 11 of 11 and schedule to graduate Jan. 19. (U.S. Air Force photo by Alan R. Quevy)