Which device limits rotor blade flap at low rotor speed or when the rotor is stopped?

Which device limits rotor blade flap at low rotor speed or when the rotor is stopped?

• A. Static Stop
• B. Dynamic Stop
• C. Rotor Lock
• D. Blade Stop

Answer: (A)

Limiting blade flap at low rotor speed or when the rotor is stopped is accomplished by a static stop. This fixed mechanical stop is built into the rotor hub or blade root to prevent the blade from flapping beyond safe travel when there isn’t enough centrifugal force to counteract gravity. It acts as a hard, unmoving barrier during low-speed conditions, protecting the blade and hub during starting, idling, or autorotation entries. In contrast, a dynamic stop engages only when the rotor is turning and speed-related forces come into play to limit flap at higher RPM, helping prevent flutter and overtravel during flight. Rotor lock is a maintenance device used to immobilize the rotor, not a normal flight-limit device. Blade stop isn’t the standard term used for this specific low-speed limitation.

Limiting blade flap at low rotor speed or when the rotor is stopped is accomplished by a static stop. This fixed mechanical stop is built into the rotor hub or blade root to prevent the blade from flapping beyond safe travel when there isn’t enough centrifugal force to counteract gravity. It acts as a hard, unmoving barrier during low-speed conditions, protecting the blade and hub during starting, idling, or autorotation entries.

In contrast, a dynamic stop engages only when the rotor is turning and speed-related forces come into play to limit flap at higher RPM, helping prevent flutter and overtravel during flight. Rotor lock is a maintenance device used to immobilize the rotor, not a normal flight-limit device. Blade stop isn’t the standard term used for this specific low-speed limitation.