The Detection of Cracks under Installed Fasteners by Means of a Scanning Eddy-Current Method

As a consequence of metal fatigue, cracks can develop and grow in operational aircraft. Periodic inspections must be made in order to detect and repair them before they reach a dangerous length. Cracks which grow from holes are a significant problem for aircraft since the wings and fuselage can contain many thousands of fasteners. Since it is impractical to remove them all, inspection must be made with them installed