Eddy current inspection probes are used for crack detection in bolt holes and the like. With the advent of high speed turbomachinery, a number of critical rotating parts are being specifically tested for cracks and related defects in their bolt hole walls. Various testing equipment have been developed to inspect for metal cracks in critical locations. Eddy current inspection is a commonly used technique for detecting discontinuities or flaws in the surface of components of a gas turbine engine.
The current method to inspect a bolt hole initially requires aligning a bolt hole inspection machine to the first bolt hole to be inspected. The existing bolt hole inspection machine is started and the system inspects a first bolt hole and automatically indexes to and inspects each subsequent bolt hole. However, in the course of manufacturing various components, bolt holes can vary slightly in spacing from a previous hole, by approximately 0.015" in any direction. It is critical with bolt hole inspection that the probe be held in a vertical position. If the alignment is at all inaccurate, the lift-off of the probe from inside of the bolt hole will give a (false) signal that the bolt hole will fail. The hole will have to be realigned and rerun to see if it will pass the limits that are set up for that part type. Every hole that fails on a part requires an additional three or more minutes to realign the probe to the hole and restart the inspection process. On average, an additional one to two hours is spent realigning the probe and restarting the inspection device due to false signals.
It would be desirable to be able to provide accurate alignment of the bolt hole inspection probe, compensating for variations in the spacing between holes. The objects, features and advantages of the present invention will become more readily apparent in the following description when taken in conjunction with the appended drawings.