Why does my fuel gauge jump back and forth?

Have you ever been flying your airplane and noticed that the fuel gauge needle is jumping back and forth?

This can be a concerning sight, especially if you’re not sure what’s causing it. And it can be very distracting, no matter how many times you’ve flown. There are a few possible reasons why your fuel gauge might be acting erratic. In this article, we’ll examine some of the most common causes:

A Faulty Fuel Sending Unit

The fuel sending unit is a component in the fuel tank that sends a signal to the fuel gauge indicating the amount of fuel in the tank. If the fuel sending unit is faulty, it can send incorrect signals to the fuel gauge, causing the needle to jump back and forth.

Sloshing Fuel

Aircraft fuel tanks are typically located in the wings and fuselage, and during flight, the fuel can slosh around inside the tanks. This movement can cause the fuel sender instrument to send an erratic signal, causing the needle to bounce until the fuel stabilizes.

Air Turbulence

In-flight turbulence can affect the movement of the fuel in the tanks, leading to fluctuations in the fuel gauge needle. Similarly, abrupt maneuvers or changes in aircraft attitude can also cause momentary variations in fuel gauge readings.

Instrument Sensitivity

Aircraft fuel gauges are designed to be sensitive to even small changes in fuel levels. This sensitivity can cause the needle to respond quickly to fluctuations, which may not be noticeable on gauges with lower sensitivity.

Gauge Accuracy

Depending on the type and age of the aircraft, the fuel gauge may not be perfectly accurate or may have some inherent jitter. The needle movement can be influenced by the gauge’s design and quality.

Electrical Interference

Electromagnetic interference or electrical noise from various aircraft systems can sometimes affect the fuel gauge readings, leading to temporary needle fluctuations.

A Loose or Corroded Connection

The electrical connections between the fuel sending unit and the fuel gauge can become loose or corroded over time. This can cause intermittent readings from the fuel gauge, leading to the needle jumping back and forth.

Faulty Components

In some cases, there could be issues with the fuel gauge or its components, such as the sender unit, wiring, or connections. Faulty components can cause erratic behavior in the fuel gauge readings.

Next Steps

It’s essential for pilots and aircraft maintenance personnel to be aware of the fuel gauge behavior and its limitations. Fuel levels should be cross-checked with other instruments, and any unusual or persistent fluctuations should be investigated to ensure the accuracy of the readings and avoid potential fuel-related issues during flight.

There is a Solution!

If you want to altogether eliminate jumping or bouncing fuel gauges, consider installing our industry-standard fuel senders. These innovative, bolt-in fuel senders are covered by our STC and will revolutionize how you depend on fuel quantity measurement. We also custom engineer fuel senders for specific applications. Call us at 541-977-1043 during normal business hours (Pacific) or contact us using our online form. Soon, you’ll be able to trust your fuel gauge again!

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About CiES Inc.

Established in 2012, CiES is now the largest supplier of aviation fuel quantity probes and senders. They are the recognized leader in the design, development, certification, and manufacture of electronic sensor solutions for original equipment manufacturers, as well as direct-to-market consumer products. Through the creative application of cutting-edge technologies, CiES creates complex end-to-end solutions. This is a company that is changing the game in aviation technology and revolutionizing the way we navigate the skies. Aiming at future growth and innovation, CiES is pushing the boundaries of what is possible.​

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