Which system permits the stopping of the main rotor blades quickly after engine shut down?

• A. Power Take-Off System
• B. Transmission Control System
• C. Rotor Brake System
• D. Throttle Control System

Answer: (C)

The rotor brake system is specifically designed to stop the main rotor blades rapidly after the engine has been shut down. This is crucial for safety and operational efficiency, as it helps to prevent the blades from spinning due to wind or residual momentum, which can pose hazards during ground operations or maintenance.

When the engine is shut down, the rotor blades can continue to rotate for a while, which is why a braking mechanism is needed. The rotor brake system applies friction directly to the rotor assembly, allowing for controlled and quick deceleration of the blades. This function is vital for ensuring that personnel can safely approach the helicopter and conduct inspections or maintenance without the risk of being struck by moving parts.

The other systems mentioned—such as the power take-off, transmission control, and throttle control systems—serve different purposes related to power distribution, engine management, and flight operations, but they do not provide the specific functionality of stopping the rotor blades efficiently after engine shutdown. Thus, the rotor brake system is the most appropriate answer to the question regarding rapid stopping of the main rotor blades.