What function do flapper valves serve in fuel tanks?

Flapper valves serve a crucial function in fuel tanks as check valves. Their primary role is to maintain the controlled flow of fuel while preventing backflow. This is essential in ensuring that fuel can move freely toward the engine during operation, but also that it cannot flow backward, which could lead to fuel starvation or contamination within the fuel system.

Flapper valves typically open in the direction of fuel flow, allowing fuel to pass through when needed. When the fuel flow is reversed or stops, the flapper closes, effectively sealing off the line and preventing any backflow. This mechanism is vital in maintaining the integrity of the fuel system and ensuring efficient operation of the aircraft.

While regulating fuel temperature, detecting leaks, and filtering contaminants are important functions in fuel management, they are not the purpose of flapper valves. Thus, the function of flapper valves as check valves is critical for the safe and efficient operation of aircraft fuel systems.