Major Components of Aircraft Fuel Systems

The aircraft fuel system is crucial to flight operations, providing the engines with a stable flow of fuel from the fuel tanks. As aircraft are constantly in changing environments with extreme conditions, the fuel system must ensure that there is always enough fuel to accommodate for any altitude, attitude, and more. For smaller aircraft, fuel systems often come in one of two types, those being the gravity-feed and fuel-pump system.

For aircraft that utilize a gravity-feed system, fuel is transported from the tanks to the engine through the use of gravity, hence its naming. These types of fuel tanks are typically installed within high-wing aircraft, and the tanks are placed within the wings themselves. As the fuel tanks are positioned above the carburetor, fuel flows from the fuel tanks and into the carburetor through natural forces. For some aircraft, however, gravity may not provide enough force to efficiently transfer fuel, and thus a fuel pump may be utilized.

Within aircraft that feature fuel-pump systems, two sets of pumps are powered by the engine in order to provide sufficient fuel for flight. With the addition of an electrically operated auxiliary pump, the aircraft can have a failsafe method of receiving fuel in the case that one of the other pumps fails. Within the cockpit of the aircraft, the pilot may have control over the auxiliary pump, creating more reliability in the system for safety means.

While gravity-fed and fuel-pump systems both operate with somewhat different characteristics, both feature many of the same components. Within both types, a fuel primer is used for drawing fuel from the tank so that it is vaporized into the cylinders before the engine is ignited. This is extremely beneficial when operating in colder conditions, as it ensures that fuel can still be vaporized even when there is a lack of heat. One important thing to know about fuel primers is that they must be secured when they are not operated, as vibrational forces can cause them to loosen. As a result of loosening, the fuel-air mixture of fuel can become overly rich, and overpriming is a condition that should be avoided.

Despite a possible difference in how fuel is drawn within an aircraft and system placement, the design of the fuel tank itself often remains the same. Fuel tanks are typically located within the wings of an aircraft in order to optimally balance weight, and openings are located near their top to create an ease of refueling. By having venting provided to the outside atmosphere, tanks can maintain equal pressure for safety means. Furthermore, overflow drains are often put in place so that fluids can expand as needed to accommodate temperature variations, protecting the engine from physical damage.

To ensure that pilots are always aware of the remaining amount of fuel left within the aircraft, fuel gauges are implemented within fuel tanks to serve as a sensing unit. Although such systems can be highly accurate in their measurements, operators should always verify the contents of their tanks visually before each flight and compare them to the fuel gauges for safety. As there may be two tanks within an aircraft, fuel selectors are another useful component  for manually controlling the draw of fuel. Typically, fuel selectors provide an option for LEFT, RIGHT, BOTH, and OFF, permitting the pilot to maintain an equal level of draw from each tank during the flight.

Beyond the tanks and other components, fuel strainers, drains, and sumps also play critical roles in ensuring the optimal flow and combustion of fuel. With strainers, contaminants and sediment are removed from the fuel, and they are collected within a sump so that they may be periodically removed from the system. With the fuel strainers, drains, and sump, operators can protect the system from blockages, increasing safety against engine stoppages. Due to their critical role in maintaining the efficiency and safety of the system, such components should always be inspected and drained before each flight to remove all contaminants.

With a healthy and robust aircraft fuel system, flight operations can be conducted efficiently. At Purchasing Synergy, we can help you secure the aviation parts and components that you need, offering you competitive pricing on all that we carry. Peruse our part catalogues at your leisure, and our team of industry experts are readily on standby to help you through the purchasing process and provide you with personalized quotes as needed, 24/7x365. Get started with us today and experience how Purchasing Synergy can serve as your strategic sourcing partner.


February 15, 2023
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