Fluorescent penetrant inspection is one form of non-destructive testing. It involves the application of fluorescent dye to the surface of an object in order to detect any possible faults. The FPI method is used in many different industries.
In the aviation industry, parts cleaning and non-destructive testing (NDT) are closely related. The surfaces of objects to be inspected during servicing and repairs are cleaned using chemical or mechanical methods to remove scale, rust and dirt. If necessary, coatings which may affect the inspection are also removed. When manufacturing new parts, objects are e.g. anodized or pickled and non-destructive testing is then used to determine the flawlessness of the parts.