Abstract: This anti-theft device has a plurality of arcuate metallic sections hingedly connected to be removably applied to an airplane propeller blade at one side of the propeller shaft and locked in place to prevent unauthorized removal. The device forms an eccentric weight mass which when the engine is operated, causes vibrations so severe that the aircraft cannot take off or fly successfully. A warning flag or banner is attached to the device and anyone at all familiar with aircraft operation will not attempt to take the plane.