True or False: Compressor instability sounds during engine start are acceptable if the PMU permits?

The statement is true because compressor instability sounds may occur during engine start, and they can be within acceptable limits as long as the PMU (Power Management Unit) allows it. The PMU monitors various engine parameters and is designed to handle some early-stage anomalies during the start sequence. If the PMU does not intervene or indicate a fault, then such sounds can be deemed acceptable under specific circumstances.

Compressor instability can manifest as unusual noises during the start-up process. These sounds should not automatically be interpreted as a failure or a fault if the rest of the system is functioning normally and the PMU has not triggered an alert. Therefore, understanding the role of the PMU is crucial in distinguishing between acceptable operational sounds and those that indicate a potential problem. This knowledge is vital for maintaining safety and ensuring the correct functioning of the engine.