What does the PMU FAIL annunciator signal?

• A. Loss of fuel pressure.
• B. Oxygen system failure.
• C. Power management unit failure.
• D. Emergency landing is required.

Answer: (C)

The PMU FAIL annunciator indicates a failure within the Power Management Unit (PMU). The PMU is responsible for controlling the engine's performance, including functions such as fuel flow and ignition timing. When the PMU encounters a fault, it cannot perform these critical functions effectively, which affects the engine's operational parameters. As a result, the illumination of the PMU FAIL light alerts the pilot that there may be issues requiring attention or possible corrective actions.

The other options do address various systems or conditions, but they do not relate directly to the PMU's function or failure, which is a specific aspect of the aircraft's control over its power management systems.