The landing gear, which is also called the undercarriage, is a complex system consisting of structural members, hydraulics, energy absorption components, brakes, wheels and tyres . Additional components attached to and functioning with the landing gear may include steering devices and retracting mechanisms. Of the many components, it is the structural members that support the heavy landing loads and stop the landing gear from collapsing under the aircraft weight. The materials must be strong enough to support heavy take-off weight when an aircraft has a full load of fuel and the high impact loads on landing. Landing gear materials must therefore have high static strength, good fracture toughness and fatigue strength, and the most commonly used materials are high-strength steel and titanium alloy