What does the APU electrical system primarily control?

The APU (Auxiliary Power Unit) electrical system primarily controls critical functions related to aircraft operations, particularly involving the engine starting process. It is responsible for providing the necessary electrical power to operate the ignition system and fuel systems during engine start-up. This includes facilitating fuel delivery to the engine, ensuring ignition is initiated, and managing the engine's acceleration as it comes online.

In addition to these functions, the APU ensures that monitoring systems are in place for engine operation, allowing for real-time assessment of engine parameters during the starting sequence. This comprehensive control is essential for the safe and efficient operation of an aircraft, as it ensures that all systems are properly aligned for the engine to start successfully. Understanding the APU's role in these areas is crucial for mechanical operations within aviation contexts, highlighting the importance of the APU in supporting aircraft performance and safety.