What is the maximum allowable percentage for NR Power-On operation?

• A. 100%
• B. 103%
• C. 105%
• D. 110%

Answer: (B)

In the context of the TH-73A and its operational guidelines, the maximum allowable percentage for NR (Rotor RPM) during Power-On operations is established to ensure safety and efficiency while maintaining the aircraft's performance within acceptable limits.

A limit of 103% NR for Power-On operations is set to allow for a margin of performance, while ensuring that the rotor system remains within tolerable operational thresholds. This value is critical because exceeding it could result in unnecessary stress on the rotor system, which may lead to mechanical failure or decreased aircraft performance.

Operating at 105% or 110% pushes the rotor system beyond the recommended safety margins, increasing the risk of overheating and structural failure. Thus, 103% serves as a balanced target that optimally utilizes engine power while maintaining rotor integrity and flight safety. This serves as a key performance standard that pilots must adhere to during flight operations.