The NR HI mode provides a greater margin for NR droop as well as ______.

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

Answer: (B)

NR droop margin is about how much rotor speed can sag before the control system or pilot actions intervene to restore it. In NR HI mode, the system is tuned to hold rotor speed higher and to tolerate a larger temporary drop without losing stability, giving more time to respond to transient loads. At the same time, the higher rotor speed means more engine and main-rotor torque that must be countered to keep yaw under control. That’s where tail rotor authority comes in—the ability of the tail rotor to produce the necessary anti-torque moment. With NR HI mode, the tail rotor is provided with more available thrust/control authority to counteract the increased torque, improving yaw control during high-power or transient conditions. Lift changes aren’t the focus of this mode; the benefit here is better rotor-speed margin and stronger anti-torque capability to maintain stable flight.