Power Push-Over
Power push-over (Buntover) is the action of an aircraft, typically a gyroplane, whose propeller thrust line is above the center of gravity and lacks an adequate horizontal stabilizer to pitch forward. Power push-over is caused by the creation of a torque around the center of mass of the gyroplane by the force of the propeller and unloading of the rotor. Unloading of the rotor and subsequent power push-over can be caused by excessive pilot-induced oscillations.