Aircraft Fuel Tank System has a critical role in ensuring flight operations and efficiency. Before taking off, ensuring the aircraft is properly refueled is crucial. Have you ever wondered where the kerosene is stored in the plane and how the placement of the fuel tanks can impact its performance?

An aircraft’s specific requirements determine the position, capacity, and configuration of fuel tanks. Smaller, single-engine aircraft typically feature fuel tanks positioned above the wing, utilizing a gravity feed system for fuel delivery to the engine (overwing fueling).

In contrast, some aircraft have tanks beneath the wing and employ pumps or fuel injection for fuel transport (underwing fueling). These tanks can exist as standalone components or seamlessly integrate into the wing structure.

There are generally three classifications for fuel tanks: integral, rigid, and bladder. Now, let’s delve into each type.

What is an Aircraft Fuel Tank System?

What is an Aircraft Fuel Tank System?

The fuel tank is an indispensable component of every aircraft. Aircraft fuel tanks are available in various designs to suit different aircraft types. Regardless of operating conditions, the fuel tank (or tanks) must be positioned optimally to store and deliver clean fuel to the engine at the correct pressure and flow rate.

The storage of flammable fluid in aircraft fuel tanks makes them critical components of fuel systems. These tanks are subjected to various stress factors, including vibration, aerodynamic forces, heat, cold, inertial loads, and even the potential for lightning strikes during flights. As a result, the fuel tanks installed on aircraft must withstand the most rigorous conditions encountered during flight without experiencing deformation, surface corrosion, or similar issues.

Overall, the aircraft fuel tank system is essential for the safe operation and efficiency of the aircraft, and pilots and engineers must have a thorough understanding of this system and maintain it with precision.

Types of Aircraft Fuel Tank System

Types of Aircraft Fuel Tank System

System complexity plays a crucial role when selecting an aircraft system architecture. There are different aircraft fuel tank systems, each serving specific functions. During aircraft refueling, nearly 800 kilograms of kerosene, almost 1,000 liters, are transferred into the tanks per minute.

Each aircraft fuel tank system type has its benefits and is engineered to address the operational requirements and structural constraints of different aircraft models—conversely, integral fuel tank (wet wings), rigid fuel tank, and bladder fuel tank. The integral fuel tank is constructed within sealed wing regions and consists of non-corrosive aluminum frames. The rigid fuel tank is built separately from the aircraft and installed in the wings or fuselage.

The bladder fuel tank is similar to the rigid tank. Still, it is made of reinforced flexible materials, such as synthetic rubber, and does not require large cuts into aircraft structures for installation.

Moreover, fuel tanks must be permanently sealed to prevent external contamination, including dirt, dust, and water, from reaching the fuel system. An aircraft refueller is usually responsible for some quality control checks.

Rigid Tanks

Aircraft fuel tanks are often rigid and removable, especially in older models. They are typically made from materials like aluminum alloy or stainless steel and are constructed to prevent leaks through riveting and seam welding. The airframe needs to be secured to avoid shifting during flight. While usually located in the wings, some tanks are integrated into the wing’s leading edge.

Newer tanks are experimenting with materials beyond aluminum and stainless steel, such as isophthalic polyester resin composite, offering seamless and lightweight constructions.

Rigid tanks undergo pressure testing to ensure they won’t leak or collapse during flight, and the removable design allows for easy repairs or replacements when necessary.

Bladder Tanks

Bladder tanks are fuel containers made of reinforced flexible materials. They are similar to rigid tanks but do not require as large of an opening in the aircraft for installation. The tank can be rolled up and inserted through a small opening, then unfolded to its full size.

Bladder tanks must be attached to the structure with clips or other fastening devices and should lie smooth and unwrinkled in the bay. These tanks are strong, have a long service life, and are used on aircraft of all sizes. They are seamless apart from the areas around installed features such as the tank vents, sump drain, and filler spout.

Integral Tanks

Integral tanks are fuel tanks that are integral to the aircraft’s structure. They are the most efficient way to carry fuel, and nearly all modern aircraft utilize this type of fuel tank.

On many aircraft, especially transport category and high-performance aircraft, a fuel-resistant two-part sealant is used to seal part of the structure of the wings or fuselage, forming a fuel tank. The sealed skin and structural members offer a high volume of space with minimal weight.

Aircraft that use integral fuel tanks typically feature sophisticated fuel systems, including in-tank boost pumps. Typically, two or more pumps in each tank fuel the engine or engines under positive. These boost pumps also transfer fuel to the other tanks, jettison fuel, and defuel the aircraft.

However, they can be more challenging to repair or replace than other fuel tank types.

Components of Aircraft Fuel Tank System

Components of Aircraft Fuel Tank System

The components of aircraft fuel tank systems play a critical role in ensuring an aircraft’s safe and efficient operation. These systems comprise various components such as fuel tanks, fuel lines, fuel pumps, fuel gauges, and fuel filters. Each element works together to store, transport, and monitor the fuel required for the aircraft’s engines.

Fuel tanks provide a secure storage space for the fuel, while fuel lines ensure fuel transportation from the tanks to the engines. Fuel pumps help to pressurize the fuel for efficient delivery, and fuel gauges provide pilots with essential information about the remaining fuel levels.

Additionally, fuel filters are essential in removing contaminants from the fuel, thereby safeguarding the engines against potential damage. These components’ intricate design and seamless operation exemplify the meticulous engineering and attention to detail required to construct aircraft fuel tank systems.

Fuel Lines

Fuel lines are the pipes or hoses that carry fuel from the fuel tanks to the engines. These lines must be designed to withstand high pressures and temperatures to ensure the proper flow of fuel.

Fuel lines are often made of stainless steel or aluminum to prevent corrosion and cracking.

Fuel Pumps

Fuel pumps are mechanical or electric devices that transfer fuel from the fuel tanks to the engines. These pumps create the necessary pressure to deliver fuel at the correct engine flow rate.

Fuel pumps are essential components of the fuel tank system and must be adequately maintained to ensure reliable operation.

Fuel Filters

Fuel filters remove contaminants such as dirt, debris, and water from the fuel before it reaches the engines. These filters help prevent engine damage and ensure the fuel system operates efficiently.

Fuel filters should be regularly inspected and replaced to maintain the integrity of the fuel system.

Fuel Gauges

Fuel gauges display the fuel remaining in the aircraft’s fuel tanks. These gauges provide critical information to the pilot, allowing them to monitor fuel levels and plan refueling stops accordingly.

Fuel gauges are essential for safe and efficient flight operations.


The aircraft fuel tank system is a complex and essential component of any aircraft. Understanding the different types of fuel tank systems and their components is crucial for ensuring an aircraft’s safe and efficient operation.

By comparing the types and components of aircraft fuel tank systems, pilots, engineers, and aviation enthusiasts can gain a better appreciation for the incredible technology that keeps aircraft flying safely through the sky.


Leave a Reply

Your email address will not be published. Required fields are marked *