Tech. Sgt. Frank Castonguay pours a fluorescent oil bath over a KC-135 Stratotanker brake key inside a magnetic field generator Feb. 11, 2014, at Royal Air Force Mildenhall, England. The oil bath coats the part in fluorescent particles, which are attracted to any cracks after a magnetic field is established on either end of the part. This method quickly allows non-destructive inspection shop members to identify dangerous defects in parts. Castonguay is a 100th Maintenance Squadron NDI craftsman. (U.S. Air Force photo/Airman 1st Class Dillon Johnston)