What is the primary function of the High-Pressure Engine-Driven Pump?

The primary function of the High-Pressure Engine-Driven Pump is to deliver fuel under pressure to the Fuel Control Unit (FCU). This pump is essential in ensuring that the fuel system maintains the necessary pressure for optimal engine performance, particularly during various phases of operation such as takeoff, climb, and cruise.

Fuel needs to be supplied at high pressure to ensure that it can efficiently atomize and mix with the incoming air for combustion in the engine, which directly affects the engine's power output and efficiency. The FCU requires this fuel at a specified pressure to regulate the engine's power and adjust mixture settings during operation.

In contrast, other options like delivering fuel under low pressure or circulating oil do not align with the specific role of the high-pressure pump, showing that its design and function are distinctly centered on facilitating the high-pressure fuel supply necessary for correct engine operation.