In aircraft maintenance programme it is important to inspect the mechanical damage and assess the extent of the repair work. But in schedule maintenance it is a difficult to finding the defects rapidly, as the maintenance of aircraft must be accomplished within scheduled time and same to be released in time for commercial operation.
During aircraft maintenance 'NONDESTRUCTWE TESTING' (NDT) is the most economical way of performing inspection and this is the only way of discovering defects. In simply we can say, NDT can detect cracks or any other irregularities in the airframe structure and engine components which are obviously not visible to the naked eye.
Structures & different assemblies of aircraft are made from various materials, such as aluminium alloy, steel, titanium and composite materials. To dismantle the aircraft in pieces and then examine each component would take a long time, so the NDT method and equipment selection must be fast and effective.
In the present trend of NDT application on aircraft 70-80% of NDT is performed on the airframe, structure, landing gears and the rest carried out on engine & related components.
In order to maintain the aircraft defects free and ensure a high degree of quality & reliability and as a part of inspection programme, usually following NDT methods are applied;
1) Liquid penetrant 2) Magnetic particle, 3) Eddy current 4) Ultrasonic 5) Radiography (x-ray/gama ray) 6) Visual/Optical 7) Sonic/Resonance 8) Infrared Thermography.
DIFFERENT NDT METHODS
1. Liquid Penetrant :
Liquid penetrant testing is one of the oldest of modern non-destructive testing methods & widely used in aircraft maintenance. Liquid penetrant testing can be defined as a physical & chemical non-destructive procedure designed to detect & expose surface connected discontinuities in 'nonporous' engineering materials.
The fundamental purpose...