In the fuel delivery sequence, what is the purpose of the engine-driven low-pressure pump feeding the oil-to-fuel heat exchanger?

• A. It heats the fuel to prevent ice and helps cool the engine oil.
• B. It pumps fuel directly to the FCU.
• C. It vents excess pressure to the atmosphere.
• D. It drains fuel back to the tanks.

Answer: (A)

The fuel system uses the engine’s hot oil to warm the fuel before it reaches the metering and delivery stages. The engine-driven low‑pressure pump pushes fuel through the oil‑to‑fuel heat exchanger, where hot engine oil transfers heat to the fuel. This warms the fuel, which helps prevent fuel icing in cold conditions, and it also cools the engine oil by transferring some of its heat to the fuel. After this heating step, the fuel continues on to the fuel control unit for metering. This is why heating the fuel to prevent ice and cooling the oil are the correct purposes of this pump‑through‑ exchanger path.