What is the purpose of the Droop Stops in the main rotor system?

• A. Increase rotor speed
• B. Improve control sensitivity
• C. Reduce vibration
• D. Limit the droop of the main rotor blades

Answer: (D)

Droop stops are there to limit how far the main rotor blades can droop when the rotor isn’t fully loaded, such as when the engine isn’t driving the rotor or during slow rotor speeds. Gravity tends to pull the blades downward, and without a limit, the blades could sag enough to interfere with the rotor head, control linkages, or the airframe. The stops engage at a defined angle to hold the blade in a safe, known position, protecting hardware and maintaining safe clearance during ground handling and engine start or autorotation.

They don’t increase rotor speed, they don’t directly improve control sensitivity, and they don’t primarily reduce vibration. Their main role is simply to prevent excessive blade droop.