Aircraft fuel systems are more complex than their automotive counterparts. While most cars, trucks and other automobiles have a single fuel tank, large commercial airliners typically have at least two fuel tanks. The Boeing 787, for instance, has three fuel tanks: one in each wing and another fuel tank at the bottom of the fuselage.
Whether an airplane has a single fuel tank or multiple fuel tanks, though, it may feature a smaller tank known as a header tank. Header tanks are particularly common in single-engine airplanes. Single-engine airplanes may still feature multiple fuel tanks, but they often have a header tank to facilitate the flow of fuel to the engine.
Overview of Header Tanks
A header tank is a fuel tank that’s found between an airplane’s engine and all of its fuel tanks. It’s often made of the same materials, and it stores the same type of fuel. Header tanks, though, are intermediary tanks. They are characterized by their location.
All header tanks are found between the airplane’s engine and its other, main fuel tanks. They are intermediary fuel tanks that supply or feed fuel to the airplane’s engine.
The Purpose of a Header Tank
Some people assume that header tanks function as auxiliary fuel tanks. If an airplane is running low on fuel, it can tap into the header tank — at least that’s the common belief. But header tanks aren’t used as backup fuel sources.
The header tank on an airplane ensures that its engine constantly has fuel. It will constantly feed fuel to the airplane’s engine. Why is this necessary exactly?
Main fuel tanks are typically found in the wings. Normally, gravity will assist in moving fuel from these wing-installed tanks to the airplane’s engine. If the airplane descends quickly, however, this may not happen. A sudden or fast descent may result in fuel getting stuck in the wing-installed tanks, thereby starving the airplane’s engine of fuel.
Header tanks are typically mounted directly above or behind the airplane’s engine. They receive fuel from the airplane’s other, main fuel tanks, which they funnel to the adjacent engine.
In Conclusion
Header tanks are secondary fuel storage tanks that feed fuel to an airplane’s engine. They are found between the airplane’s engine and its main fuel tanks. Even if the airplane quickly changes its altitude or attitude, its engine will continue to work thanks to the fuel provided by the header tank.
