What do Anti-Flap Assemblies prevent?

• A. Prevent main rotor blades from flapping when the rotor head is slowing down or at a complete stop
• B. Increase blade pitch
• C. Filter vibrations
• D. Adjust tail rotor stiffness

Answer: (A)

Anti-flap assemblies limit the upward flutter of the main rotor blades as rotor speed decreases or when the rotor is near a stop. By providing stops or dampers in the hub, they constrain flap motion so blades don’t strike the rotor head or adjacent blades during deceleration or at rest. This keeps the rotor system safe during low-speed or stationary conditions. They aren’t involved in changing blade pitch, filtering vibrations, or adjusting tail rotor stiffness.