What malfunction would likely lead to fluctuating N1 readings in the TH-73A?

• A. Overspeed
• B. Compressor Stall
• C. Low fuel pressure
• D. High ITT

Answer: (B)

Fluctuating N1 readings in the TH-73A can be attributed to a compressor stall. During a compressor stall, the airflow through the engine is disrupted, leading to a momentary loss of engine power. This disruption causes the engine parameters, including N1, which indicates the speed of the engine's low-pressure turbine, to fluctuate because the engine is not operating smoothly at the expected performance levels.

Compressor stalls can happen due to various reasons, including sudden changes in aircraft attitude, abrupt throttle movements, or insufficient airflow. When a stall occurs, it can lead to variations in engine speed as the engine management system attempts to correct the airflow and restore stable operation, resulting in the fluctuating N1 readings observed.

Understanding this phenomenon is crucial for flight safety and engine performance management, as unstable N1 readings could indicate an underlying issue that needs to be addressed to maintain optimal engine performance.