Which fuel system supplies the APU during normal operation?

The fuel system supplying the Auxiliary Power Unit (APU) during normal operation is the Engine 1 fuel supply line. This system is designed to ensure that the APU receives an adequate fuel supply for its operation, especially when the aircraft is not in flight and the engines are not running.

In the context of the Dassault Falcon 2000LXS, the APU typically relies on fuel from the engines' supply lines. This setup allows for a seamless transition in fuel availability, benefiting operational efficiency. While other options may involve components of the fuel system, the Engine 1 fuel supply line is specifically configured to provide fuel to the APU in normal operational situations, making it the correct choice.

Understanding the role of the fuel supply lines and their function in different operational scenarios is crucial for effective aircraft performance and maintenance. This knowledge ensures that crew members can manage fuel supply efficiently for both the APU and the main engines as needed.