180508-F-OT290-0007
U.S. Air Force Airman 1st Class Aaron Haar, 52nd Maintenance Squadron non-destructive inspection apprentice, submerges F-16 aircraft screws into penetrant at Spangdahlem Air Base, Germany, May 8, 2018. Penetrant is a fluorescent liquid used to penetrate cracks, pores, and other surface defects to facilitate their detection. (U.S. Air Force photo by Airman 1st Class Jovante Johnson)