The aerospace industry uses nondestructive testing (NDT) methods quite extensively. The structural integrity and safety of nearly all components, especially the most critical ones, needs to be validated and NDT plays a major role. NDT is required in virtually all areas of newly manufactured, serviced, repaired, or overhauled inspections.
There are a variety of NDT methods used in aerospace and most of these can be divided into two categories: surface and sub-surface. The surface methods are used to detect on surface or very near the surface defects and anomalies. Two of the most heavily used surface methods include penetrant inspection and laser shearography. Sub-surface methods are those that identify below the surface defects. Two of the most used techniques are radiography and ultrasonic inspections. A few methods, like ultrasonic and electromagnetic testing, can be used for both surface and subsurface inspections, so they can fit into each bucket as needed. There is also one other type of method, the acoustic resonance method, that is a full-body inspection, meaning it can assess the overall structural integrity of an entire component.