What is the function of DC fuel pumps in aircraft systems?

The function of DC fuel pumps in aircraft systems primarily relates to their role in supplying fuel to the engines and auxiliary power unit (APU) during critical phases of operation. When starting the APU and the engines, these pumps ensure that fuel is delivered at the appropriate pressure and flow rate necessary for combustion and propulsion.

During the start sequence, the DC fuel pumps help to maintain fuel flow even if the engines or APU are not yet running. This is crucial for a successful ignition and safe operation, especially in the context of regional jets where efficient and reliable start procedures are vital for operational efficiency. The ability of the DC fuel pumps to provide a consistent and adequate fuel supply directly influences the performance and safety of the aircraft during engine start.

In contrast, other functions associated with the remaining choices do not directly pertain to the primary purpose of DC fuel pumps. For example, fuel heating control is managed by different systems to prevent fuel freezing at high altitudes, and powering the electrical system is not a function of fuel pumps but rather of generators and batteries. Additionally, enabling hydraulic pressure is the responsibility of hydraulic pumps, not fuel pumps.

Thus, the involvement of DC fuel pumps in starting the APU and engines is the correct understanding of their function within