What is the primary function of fuel boost pumps?

The primary function of fuel boost pumps is to provide constant fuel pressure. These pumps are critical in maintaining the proper fuel flow to the engine, especially during the initial start-up and at low engine speeds when fuel demand is lower. By ensuring that fuel is delivered at a consistent pressure, boost pumps help prevent vapor lock and ensure that the fuel control system operates effectively.

In contrast, the other functions mentioned are not related to the purpose of boost pumps. For instance, while engines may require proper cooling, the boost pump's role does not involve cooling the engine directly. Similarly, while achieving increased engine power is a goal of overall fuel delivery and combustion efficiency, it is not the direct function of the boost pump. Finally, filtering impurities from fuel is a separate task typically handled by fuel filters rather than by boost pumps themselves. Thus, ensuring stable fuel pressure is the crucial role of fuel boost pumps in aircraft engines.