Non-Destructive Inspection (NDI) methods are employed in the repair process of composite and adhesively bonded structures in three ways: damage location, damage evaluation, that is type, size, shape and internal position of the damage and post-repair quality assurance. Assessment of the damage is usually initially achieved by visual inspection during a structure walk-around survey. The majority of NDI methods available for composite laminates and adhesively bonded structures have been used successfully with metallic structures. The implementation of ultrasonic inspection can range from inexpensive to quite costly in terms of the equipment requirements. Thermography as an NDI technique that measures the response of a structure to thermal energy dissipation. Passive thermography is when heat is applied to the structure, and the thermal wave can be visualised on an infrared camera. The two main radiation NDI methods used in composite sandwich structures are x-ray and neutron radiography, x-ray radiography being the most common.