Which indication might accompany a compressor stall?

A compressor stall often occurs due to airflow disturbances within the engine, leading to a reduction in performance. One of the key indicators of this condition is an increase in Interstage Turbine Temperature (ITT). When a stall happens, the engine may struggle to maintain a proper fuel-air mixture due to the disturbed airflow, which can cause the combustion process to become less efficient. As a result, the temperature in the combustion chamber increases, leading to an increased ITT reading.

In contrast, high RPM, stable torque, and fluctuating speed do not directly indicate a compressor stall. High RPM could suggest that the engine is operating normally, while stable torque would indicate consistent engine performance, and fluctuations in speed might represent normal operational adjustments rather than a stall condition. Hence, the increase in ITT is a clear and relevant indicator that points towards the occurrence of a compressor stall, making it the most accurate answer.