The rotor brake must only be operated below which of the following limits?

• A. 30 %
• B. 40 %
• C. 20 %
• D. 25 %

Answer: (B)

The rotor brake must only be operated below 40 percent of rotor speed to ensure safe operational practices. This limit is crucial because engaging the rotor brake at higher speeds could result in excessive wear or damage to the brake components, as well as instabilities in the rotor system. At speeds above this threshold, the forces acting on the rotor blades increase significantly, which can lead to loss of control and potentially hazardous situations. Operating the rotor brake below this limit provides enough margin to effectively decelerate the rotor without risking the integrity of the braking system or the overall safety of the aircraft. The 40 percent threshold is established as a standard that balances effective braking performance with mechanical safety, minimizing the chances of mechanical failure and enhancing pilot control during the aircraft’s operation.