A U.S. Air Force non-destructive inspection apprentice assigned to the 1st Maintenance Squadron clears data on an optical emission spectrometer before analyzing aircraft oil at Langley Air Force Base, Va., Sept. 22, 2015. The spectrometer computer analyzes the intensity of light and colors emitted by burning aircraft oil to determine the type of metallic elements contained in the oil. (U.S. Air Force photo by Senior Airman Aubrey White/Released)