The TRNG safety feature ensures the idled engine can provide power up to the ____ stop to prevent excessive NR droop below 320 RPM.

• A. ACTUAL SELECTED OEI STOP
• B. DESIRED OEI STOP
• C. MAXIMUM OEI STOP
• D. MINIMUM OEI STOP

Answer: (A)

When operating with one engine inoperative, the helicopter must have a defined power limit that tells how much the idled engine needs to contribute to keep rotor speed above a safe level. The TRNG safety feature guarantees the idled engine can provide power up to the actual selected OEI stop. This ensures there is enough torque from the idle engine to prevent excessive NR droop below 320 RPM. The actual selected OEI stop reflects the current flight conditions and limits, so it’s the correct reference for safeguarding NR. The desired stop is just a target, while the maximum or minimum stops are either extreme boundaries rather than the active limit used for this purpose.