What might be unavailable if the PMU status annunciator is illuminated?

• A. Engine start
• B. Auto abort function
• C. Fuel pressure
• D. Landing gear deployment

Answer: (B)

The PMU (Power Management Unit) status annunciator indicates that there is a malfunction within the PMU system which could affect various functions of the aircraft. When this annunciator is illuminated, it suggests that the system may have to resort to default settings or limitations for engine operation and performance, which includes critical safety features.

One of the significant functions likely to be unavailable while the PMU status annunciator is illuminated is the auto abort function. The auto abort feature is designed to automatically shut down the engine in the event of a critical failure, such as an engine fire or other emergencies that require an immediate response. If the PMU is experiencing an issue, it may not be able to reliably assess the engine’s parameters necessary to execute this function, therefore compromising safety.

Understanding the implications of the PMU status annunciator is crucial for pilots because it alerts them to potential vulnerabilities in the engine's operational management, necessitating alternative procedures to ensure safety and performance.