The lift capability of the rotor system is limited by the actual collective stop and NR will not increase above ______ RPM in the Training Mode until the collective is reduced to a power level below the good engine topping.

• A. 320 RPM
• B. 300 RPM
• C. 360 RPM
• D. 400 RPM

Answer: (A)

The key idea is how rotor speed (NR) is tied to collective demand and engine power in Training Mode. When the collective is pushed up to the actual stop, the rotor system is demanding maximum lift, which increases rotor torque and drag. If the engine is at or near its topping limit, there isn’t enough available power to push NR higher. That’s why NR won’t rise above a fixed ceiling—320 RPM—while the collective remains at that stop.

To allow NR to increase beyond that point, you must reduce the collective so the rotor load decreases and the engine is no longer at good engine topping, freeing power to accelerate the rotor. So 320 RPM is the limit under those Training Mode conditions.