U.S. Air Force Airman 1st Class Michael Griffin, 1st Maintenance Squadron nondestructive inspection technician, utilizes a stationary penetrant line at Langley Air Force Base, Va., Nov. 3, 2014. A penetrant is used to detect discontinuities, i.e., cracks and pits, open to the surface on parts made of nonporous materials. (U.S. Air Force photo by Staff Sgt. Antoinette Gibson/Released)