What is the primary purpose of the auxiliary fuel pump in the aircraft's fuel system?

The auxiliary fuel pump's primary role in an aircraft's fuel system is to increase fuel pressure. This pump is typically used during critical phases of flight, such as engine start-up and takeoff, to ensure that the fuel system delivers an adequate and consistent fuel flow to the engine. When the main pump is not operating or when additional pressure is needed, the auxiliary pump serves to maintain the necessary fuel flow for engine operation.

In addition to its primary function, this pump also plays a vital role in troubleshooting situations where fuel flow might be insufficient due to malfunctions in the primary fuel system. By increasing fuel pressure, the auxiliary pump helps prevent engine stall or surging, ensuring smoother operation. Understanding this function is essential for pilots as it relates to aircraft performance and safety during various flight stages.