NR HI mode is described as providing greater margin for NR droop and which other capability?

• A. increased engine performance
• B. increased tail rotor authority
• C. increased torque margin
• D. significantly greater lift capability

Answer: (B)

In NR HI mode, the rotor speed is held at a higher reference, which gives more headroom against rotor-speed droop and increases the tail rotor’s effectiveness. When the rotor is kept higher, a sudden increase in torque or a heavy collective demand won’t push the rotor speed toward the minimum as quickly, because there’s a larger margin before NR droops. At the same time, the higher rotor speed and maintained power flow mean the tail rotor has more available thrust to counteract the main rotor’s torque, improving yaw control. So this mode directly enhances both droop margin and tail rotor authority, rather than primarily affecting engine performance or lift.