Airman 1st Class James Rogers, 437th Maintenance Squadron Non-Destructive Inspector journeyman from Joint Base Charleston, S.C., conducts a Magnetic Particle Inspection on a break bolt, June 26, 2012. MPI relies on the principle of magnetism. Small ferrous particles suspended in oil or water is attracted to magnetic field leakage sites. Cracks and similar discontinuities cause disruptions in the magnetic field of magnetized parts attracting ferrous particles to the leakage site allowing Rogers to visualize where the discontinuities are located in the part.