Probe Typesįixed Sliding Probes These probes are generally used for thinner material compared to the adjustable probes. In order to make a complete inspection there must be two scans that are orthogonal (90 degrees) to each other. The probes are marked with a detection line to indicate the direction of inspection. They are capable of detecting surface and subsurface discontinuities, but they can only detect defects in one direction. Sliding probes are one of the fastest methods to inspect large numbers of fastener holes.
This means that the eddy currents are induced by the driver coil and detected by a separate receiving coil. There are two types of sliding probes, fixed and adjustable, which are usually operated in the reflection mode. Sliding probes have been named so because they move over fasteners in a sliding motion. In order to inspect the fastener holes in an adequate amount of time, sliding probes are an efficient method of inspection. Because of the fatigue stress that is caused by the typical application of any commercial aircraft, fatigue cracks can be induced in the vicinity of the fastener holes.
Many commercial aircraft applications involve the use of multiple fasteners to connect the multi-layer skins. Surface Crack Detection Using Sliding Probes Surface Crack Detection Using Sliding Probes