Fuel is normally supplied to the APU from which source?

The correct answer indicates that fuel is typically supplied to the Auxiliary Power Unit (APU) from the left fuel feed line. This setup is designed to ensure that the APU receives fuel from the appropriate source in a manner that is efficient and reliable. The left fuel feed line is specifically positioned to provide fuel to the APU when it is operational, which optimally supports its power generation capabilities during ground operations or in flight as needed.

In many aircraft designs, particularly in commercial jets like the A320, specific systems are configured to draw fuel from designated tanks or lines to maintain consistent and reliable operations. The inclusion of the left fuel feed line as the source is often part of a system designed for safety and operational efficiency.

Understanding the fuel supply chain for the APU is critical as it highlights how various components of the aircraft interact to ensure efficient performance. The APU relies on this dedicated feed to maintain its functionality independently of the engines and the rest of the aircraft's power systems.