Inspection of flight control surfaces made by honeycomb sandwich panels with use of Thermography method and Air Injection

Usage of composite materials in aircrafts is increasing because of lightweight, strength and other appropriate physical properties. Vertical Rudder and Horizontal Elevator usually made by Honeycomb composite sandwich panels. These surfaces may be affected by defects due to crossing different climatic conditions and aging. In addition, detection of accumulated water droplets is so important. Although the using of conventional nondestructive inspection test methods such as Ultrasonic is so common, but concerning the restrictions, would not be enough. Checking for the changes of elastic properties cannot lead to the detection of water droplets in the internal network and defects too. The most common way to ensure the absence of these defects is using the Thermography method. Thermography is based on the specific thermal properties of materials and thermal equilibrium point. Airbus has used the two methods of Lock-in Thermography and Pulse Thermography in order to inspect possible defects in Rudders and Elevators. As well as describing the inspection principals in using this method, the current article studies the possibility of using the Air Injection for inspecting these surfaces.