Returning the TRNG switch back to the flight position should be completed with the PFD Torque Display less than what percent and NR stable at which RPM?

Returning the TRNG switch back to the flight position should be completed with the PFD Torque Display less than what percent and NR stable at which RPM?

• A. 40% and 355 RPM
• B. 40% and 365 RPM
• C. 30% and 355 RPM
• D. 50% and 355 RPM

Answer: (A)

When you return the TRNG switch to flight, you want the system to come back online without placing a heavy transient load on the rotor. The PFD Torque Display should be under 40% so the rotor isn’t carrying a sudden, high torque demand as electrical power is reestablished. At the same time, the rotor speed (NR) should be stable at 355 RPM, which represents a safe, settled rotor speed region for re-engaging flight power and ensures the engine-driven systems have reached a stable condition before full power is restored. If the torque is higher or the NR is at a higher, less stable value, the re-engagement could induce unnecessary stress or instability, so the specified combination of less than 40% torque and NR stable at 355 RPM is the proper target.

When you return the TRNG switch to flight, you want the system to come back online without placing a heavy transient load on the rotor. The PFD Torque Display should be under 40% so the rotor isn’t carrying a sudden, high torque demand as electrical power is reestablished. At the same time, the rotor speed (NR) should be stable at 355 RPM, which represents a safe, settled rotor speed region for re-engaging flight power and ensures the engine-driven systems have reached a stable condition before full power is restored. If the torque is higher or the NR is at a higher, less stable value, the re-engagement could induce unnecessary stress or instability, so the specified combination of less than 40% torque and NR stable at 355 RPM is the proper target.