AT a manufacturing stage or to ensure the continued airworthiness of an aircraft's components, non‐destructive testing (NDT) occupies an important place in any inspection programme. By means of the methods employed, parts can be inspected and returned to service with confidence in their ability to fulfil a role in a system or structure. Also of significance is the early detection by NDT methods of potential defects so that preventative measures can be immediately implemented. This is particularly important where engine components are concerned in which high stress levels are part of the normal operating environment together with creep and fatigue in several forms.