How does the APU fuel system manage fuel during starting and acceleration?

The APU (Auxiliary Power Unit) fuel system is designed to provide fully automatic fuel flow during the operation, including starting and acceleration phases. This automation is crucial for ensuring that the APU operates efficiently and responds appropriately to the varying demands placed on it during these critical phases of operation.

When starting the APU, an automatic fuel flow system ensures that the correct amount of fuel is delivered to the combustion chamber without the need for manual input from the pilot or crew. This automatic management helps in achieving a reliable and consistent start, minimizing the risk of starting failures or inefficiencies that could arise from manual adjustments.

During acceleration, the automatic fuel flow continues to function seamlessly, adjusting the fuel supply based on the APU's operational requirements and performance parameters. This ensures optimal operation across a range of conditions, allowing the APU to quickly adapt to changes in demand without requiring constant human oversight.

The fully automatic nature of the fuel flow not only enhances operational safety and reliability but also reduces pilot workload, allowing the aircrew to focus on other critical tasks during flight operations.