Which flight condition occurs when the main rotor is driven only by aerodynamic forces with no engine power?

Which flight condition occurs when the main rotor is driven only by aerodynamic forces with no engine power?

• A. Autorotation
• B. Autopilot
• C. Axis of Rotation
• D. Blade Damper

Answer: (A)

Autorotation is the condition where the main rotor remains turning and generating lift solely from the airflow through the rotor blades, with no engine power driving the rotor. When power is lost, the transmission’s freewheeling unit uncouples the rotor from the engine, so the rotor is driven by the helicopter’s descent and forward airspeed. The upward relative wind through the rotor keeps it turning, and the pilot manages rotor RPM by adjusting collective pitch. This configuration lets the rotor energy be maintained and used to perform a controlled landing despite an engine failure. The other terms don’t describe this situation: autopilot is a flight control system that automatically manages aircraft attitude or flight path; the axis of rotation is a geometric line about which a body rotates; and a blade damper is a device to reduce vibration in the rotor system.

Autorotation is the condition where the main rotor remains turning and generating lift solely from the airflow through the rotor blades, with no engine power driving the rotor. When power is lost, the transmission’s freewheeling unit uncouples the rotor from the engine, so the rotor is driven by the helicopter’s descent and forward airspeed. The upward relative wind through the rotor keeps it turning, and the pilot manages rotor RPM by adjusting collective pitch. This configuration lets the rotor energy be maintained and used to perform a controlled landing despite an engine failure.

The other terms don’t describe this situation: autopilot is a flight control system that automatically manages aircraft attitude or flight path; the axis of rotation is a geometric line about which a body rotates; and a blade damper is a device to reduce vibration in the rotor system.