What is the function of a fuel heater in an aircraft fuel system?

The function of a fuel heater in an aircraft fuel system is primarily to protect the engine fuel system from ice formation. In aviation, as fuel is used, its temperature can drop significantly, especially in high-altitude operations. This drop in temperature can lead to the formation of ice within the fuel lines or filters, which can obstruct fuel flow and negatively impact engine performance.

The fuel heater works by warming the fuel before it reaches critical components of the fuel system and the engine. By raising the temperature of the fuel, it reduces the risk of ice crystals forming from the moisture that may be present in the fuel. This is particularly important to ensure that the fuel supply remains consistent and sufficient for engine operation, especially in colder temperatures.

The other options do not accurately reflect the primary role of a fuel heater. While it is essential for fuel to maintain its pressure and to prevent evaporation, those functions are served by different components within the fuel system. The cooling of fuel before it enters the engine is also not a function of a fuel heater, as heaters are specifically designed to raise the fuel temperature rather than lower it.