What Are Aircraft Fuel Gauges?

Within the aviation realm, aircraft fuel gauges are instruments used to indicate the amount of fuel in a fuel tank. Such information is critical for the aircrew to acquire, allowing them to carry out standard flight operations with ease. As running out of fuel is the leading cause of engine failure, ensuring that fuel levels are accurately measured is critical.

While aircraft are equipped with other systems that provide indications about fuel levels, gauges are typically the instruments of choice. That being said, there are three basic types, those of which include mechanical, electrical, and digital fuel gauges. In this blog, we will provide a brief overview of each, allowing you to better understand how aircraft fuel gauges function.

To begin, mechanical fuel gauges utilize a cork as their fuel indicator element. Usually made of Nitrile rubber, the cork floats on top of the fuel within the reservoir. When the fuel level goes up or down, the cork moves up and down as well. The cork itself is attached to the end of a lightweight pipe that is made of tempered aluminum. As the cork moves, so does the pipe. The pipe is attached to a stainless steel gear system.

Through the gear system, the up and down movement of the pipe is converted into circular motion that is passed through a cable affixed to the fuel gauge via a drive magnet. Finally, this entire process provides a visual indication, usually displayed as “full” or “empty” on the fuel gauge. Though mechanical gauges were predominantly used in older aircraft, they find use in older model cars today. However, due to mechanical fuel gauges having many moving parts, the likelihood of jamming or disconnecting is high.

In contrast, electrical fuel gauges, or capacitance meters, do not have any moving parts. Instead, their main components consist of a capacitor, electrical amplifier, and fuel gauge. The capacitor stores an electric charge that corresponds to a dielectric. As the fuel-air ratio changes, so does the capacitance. In turn, the fuel gauge reads the capacitance charge, and the appropriate fuel information is displayed on the instrument panel within the cockpit.

The last fuel gauge type that will be covered in this blog is of the digital variety. When aviation fuel flows through a pipe, flow rate can be measured with a high degree of accuracy. Once the aircraft is fueled up, the pilot can manually enter the total quantity of fuel per tank into the digital fuel gauge via a touch-screen keypad.

As fuel flows through the fuel outlet pipes, the onboard computer tracks fuel flow and deducts this from the total quantity inside the tank. The onboard computer digitally displays the fuel quantity in digital figures or as bar graphs. Since everything is displayed in real time, pilots know with confidence if they have enough fuel to reach their destination.

If you find yourself in need of fuel gauges, pressure gauges, or other related instruments, look no further than Aerospace Aces. Aerospace Aces is a premier distributor of aviation products, NSN components, and electronic parts, all of which are subject to rigorous quality assurance measures, tests, verifications, and assessments. With over 2 billion new, used, obsolete, and hard-to-find items at your disposal, you can find everything you need with ease. Coupled with our NO CHINA SOURCING pledge, customers can trust in the integrity of our inventory. Browse our catalogs and request a quote on any item that sparks your interest. Within 15 minutes of submission, a dedicated account manager will reach out with a customized solution that keeps your operational requirements in mind. Kickoff the procurement process today and see why customers depend on Aerospace Aces time and time again. 


January 10, 2024

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