The term 'Palindromic Helicopter Part' refers to the ROTOR of a helicopter, which is a five-letter word. The ROTOR is the main component of a helicopter that provides lift and propulsion. It consists of two or more blades that spin around a central hub, allowing the helicopter to move through the air. The blades are usually made of composite materials such as carbon fiber or aluminum. The ROTOR is powered by an engine, which is connected to the hub via a transmission system. The ROTOR is also responsible for controlling the direction of the helicopter.