The use of conventional NDE techniques for aircraft structures covered with appliqué film

Corrosion protection and rectification continue to be major elements in the life-cycle costs of aircraft. As an alternative to paints for the, protection of aircraft, the use of applique films could result in considerable cost savings. The aim of this work is to assess how the use of applique films will affect conventional non-destructive evaluation (NDE) techniques. The effect of applique film has been investigated for the following methods of NDE; ultrasonic inspection, eddy current inspection and X-radiography. For the application of ultrasonic NDE techniques, it is important to ensure that the applique film is well-bonded to the underlying structure and has low ultrasonic attenuation. For eddy current inspection techniques, the applique layer should be as thin as possible to minimise loss of measurement sensitivity. X-radiography is not significantly affected by the presence of the applique film.