The aviation industry uses a large variety of gears. The choice of gears depends on the kind of airplane or helicopter that needs to be serviced. Even within airplanes, there are a wide variety of designs, systems and internal architecture, which use an amazing array of gears and other precision tools that are made from a variety of materials including stainless steel, plastic, brass and steel. The most common types of gears used in the aviation industry are spur gears, pinion gears, rotor gears, face gears, ground gears and gear hardened. The specialty of these gears is that they can work effectively even without adequate lubrication, which makes these gears useful and reliable. Moreover, gears used in the aviation industry are strong, rigid and have high resistance against shock load.