Crews control
Senior Airman Chris McLean, 5th Aircraft Maintenance Squadron crew chief, tightens a bolt on a B-52H Stratofortress engine cowling at Minot Air Force Base, N.D., Dec. 6, 2017. During cold weather, crew chiefs are required to work a total of 30 minutes on and 30 minutes off every hour for safety. (U.S. Air Force photo by Airman 1st Class Alyssa M. Akers)