Magnetic Flux Leakage (MFL) methods are used to detect localized phenomena such as surface or sub-surface cracks in ferromagnetic materials [1]. A dc magnetic field is induced inside the sample being tested, and the distribution of the resultant lines of magnetic flux is determined by the values of magnetic permeability within the region of interest. Characteristically, the magnetic flux“leaks” out of the object in the region of a defect, allowing it to be detected using some kind of magnetic sensor.