When the Fan Stops Turning

Perhaps the most pervasive myth about helicopters is that when they lose engine power, they’re doomed to crash. In reality, a helicopter pilot has plenty of landing options open to him if the engine goes south—but he has to be on his toes.

Even without engine power, helicopters can glide to the ground using a principle called autorotation. But it’s a maneuver that requires a lot of skill and a refined sense of timing, and pilots have to spend many hours practicing such landings.

When the engine is working correctly, it pulls air from above the main rotor and accelerates it downward using the angled blades of the rotor to generate lift. When the engine fails, though, the pilot must control the helicopter so that the direction of the wind through the rotor comes from below. That wind helps keep the rotor turning and producing enough lift to allow the helicopter to glide.

As the pilot nears the ground for an autorotation landing, he doesn’t have any engine power, so he has to make his one landing attempt count. Just before the helicopter reaches the ground, the pilot uses the cyclic pitch control to tilt the rotor toward the tail. That motion allows the rotor to generate extra lift for a few moments and slows the downward speed. The pilot must have accurate timing. If he’s done it right, that extra lift comes just in time to set the helicopter down safely. Good pilots make it look easy, but an autorotation landing can frazzle a student pilot’s nerves.

When the Fan Stops Turning

Helicopters like this CH46E Sea Knight use two main rotors rather than one, eliminating the need for an antitorque rotor and increasing the amount of weight it can carry.

(U. S. Marine Corps photo)

When the Fan Stops Turning

Plane Talk

Actor Harrison Ford learned firsthand how risky autorotation landings can be. In summer 1999. he and a flight instructor were practicing the maneuver at a small airport northwest of Los Angeles when something went wrong. The helicopter, a Bell 206 Jet Ranger, crash – landed in a dry riverbed and toppled over on its side. The actor and his instructor both walked away from the crash.

When the Fan Stops Turning

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