“As the helicopter fell, its dead rotors started to spin, and Ruvola used that energy to slow the aircraft down. Like downshifting a car on a hill, a hovering auto-rotation is a way of dissipating the force of gravity by feeding it back through the engine. By the time the helicopter hit the water it had slowed to a manageable speed, and all the torque had been bled out of the rotors;.”
