Different Types of Aircraft Fuel Tanks

Aircraft fuel tanks hold the necessary amount of fuel that allow airplanes to reach their intended destinations with ease. As there are varying types of aircraft, there are numerous fuel tank options, some of which include integral, rigid removable, and bladder tank variations. That being said, this blog will outline each type and their unique features.

Integral Fuel Tanks

On transport category and high performance aircraft, part of the wing and fuselage structures are encapsulated with a fuel resistant two-part sealant to form the fuel tank. The sealed skin and structural components provide the highest volume of space available while remaining lightweight in design. This type of tank is called an integral fuel tank since it incorporates the tank as part of a unit within the airframe.

In some instances, integral fuel tanks are located in the unused space within the wings and are called wet wings. To manage fuel consumption, the wing may be sealed into separate tanks, such as a surge tank or an overflow tank, which are usually empty, but sealed to hold fuel when needed. When an aircraft banks in any direction, the long, horizontal nature of an integral wing tank necessitates baffling to prevent internalized fuel from sloshing. As such, baffle check valves may also be used, allowing fuel to move to the low, inboard sections of the tank while preventing it from moving outboard. The valves ensure that fuel boost pumps positioned at the bottom of the tanks always have fuel to pump, regardless of aircraft altitude.

Integral fuel tanks must also have access to panels for inspection and repairs. On large aircraft, technicians physically enter the tank to carry out maintenance procedures. Before performing such inspections, all fuel must be emptied from the tank. Next, fuel vapors must be purged from the reservoir, and respiratory equipment must be used. A full-time spotter must be available just outside the tank to assist if needed.

Rigid Removable Fuel Tanks

Many aircraft utilize a rigid tank which is often made of various materials and is affixed to the airframe. The tanks are usually riveted or welded together to prevent leaks, and they are typically made from 3003 or 5052 aluminum alloy or stainless steel. Early versions were made of a thin sheet steel coated with a lead/tin alloy called terneplate.

Regardless of their construction, they must always be supported by the airframe structure and secured in place with a padded strap arrangement to resist shifting during flight. Similar to integral tanks, they are popularly positioned in the wings. For maintenance, the tank must be washed out with water and detergent, and steam or water should be run through the tank. Once the proper repairs have been carried out, the fuel tank should be pressure checked to prevent distortion.

Bladder Fuel Tanks

Bladder tanks are made of reinforced flexible materials, and they contain most of the features and components of a rigid tank. However, they do not require as large of an opening in the aircraft skin to install them. The tank can be rolled up and put into a structural bay or cavity through a small opening, like an inspection opening. Once inside, the tank can be spread to its full size in a smooth and unwrinkled manner so that fuel contaminants do not settle into the tank sump. Additionally, bladder tanks must be mounted to the structure with clips or other fastening devices.

This type of tank is common on aircrafts of all sizes. More than that, they are strong and have seams around the tank vents, sump drain, filler spout, and other features for additional reinforcement. If the bladder tank develops a leak, a technician can patch it following the manufacturer’s instructions. First, the tank can be removed and sent to a fuel tank repair station. The flexible nature of such tanks requires that they remain wet. If the tank has to be stored, it can be emptied, and the inside can be wiped with a coat of clean engine oil.

Conclusion

Automatize Industrials is a leading distributor of aircraft fuel system components and aircraft fuel pump parts that have been sourced from thousands of reputable manufacturers across the globe. With over 2 billion ready-to-purchase items in our inventory, we have the ability to provide customers all that they require to fulfill their part requirements. Kickoff the procurement process with a competitive quote which can be accessed via our Instant RFQ form and see why customers rely on us for all their operational needs. 

1. rafael goodwin
2. Posted on April 25, 2022
aviation

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