NR HI mode provides which advantage during demanding low-speed maneuvers?

• A. Increased Engine Performance
• B. Increased Tail Rotor Authority
• C. Increased Torque Margin
• D. Significantly Greater Lift Capability

Answer: (B)

The main idea being tested is that NR HI mode increases rotor speed to boost tail rotor authority, which is crucial for yaw control in tight, slow maneuvers.

During demanding low-speed work, the helicopter’s ability to counter main rotor torque depends on how much thrust the tail rotor can produce. At low speeds, tail rotor effectiveness can be limited, making precise yaw control difficult. When NR HI mode is engaged, the rotor runs at a higher speed, increasing the available tail rotor thrust for the same pedal input. This grants the pilot greater yaw control authority, allowing smoother, more controllable low-speed maneuvers such as hover in tight spaces or slow, precise corrections.

This improvement focuses on tail rotor effectiveness, not on engine power output, overall lift capability, or torque margin in general, so the most direct and useful benefit in these scenarios is the increased tail rotor authority.