In aircraft fuel systems, what is the main function of a fuel filter?

• A. To regulate fuel pressure
• B. To remove particulates and protect the engine from contaminants
• C. To monitor fuel temperature
• D. To mix fuel additives

Answer: (B)

The main concept is that fuel filters cleanse the fuel to protect the engine from damage and flow issues. In an aircraft, fuel can carry dirt, rust, and even small amounts of water. If these contaminants reach pumps, injectors, or metering components, they can cause wear, clogging, or improper fuel delivery, which can degrade performance or lead to engine failure. The filter traps particulates and, in many systems, works alongside a water separator to remove free water, keeping fuel clean and ensuring smooth, reliable combustion. The other functions listed—regulating fuel pressure, monitoring temperature, or mixing additives—are handled by separate components or systems, not the filter.