What is the primary power source for the PMU?

The primary power source for the PMU, or Power Management Unit, is indeed the Permanent Magnet Alternator (PMA). The PMA plays a critical role in the T‑6B aircraft's electrical system by generating electrical power necessary for the operation of various systems, including those monitored and managed by the PMU.

The PMU requires a reliable source of power to perform its functions, which include management of engine performance parameters and providing data to the cockpit displays. The PMA generates AC power, which is then rectified to DC power to be used by different components in the aircraft’s systems.

In contrast, the generator bus, battery bus, and engine data manager have different primary functions. The generator bus is responsible for distributing power generated by the engine-driven generators and is not the primary source. The battery bus supplies power from the aircraft's battery, which is intended for backup power rather than primary operational use. The engine data manager serves to process data related to engine performance but does not serve as a power source.

Thus, the role of the PMA as the primary power source aligns with its purpose in supporting the functionality of the PMU and the overall electrical system of the T‑6B aircraft.