AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

What Is a Fuel Flow Transducer in Aircraft and How Does It Work?

Many types of transducers can be found on an aircraft, but one of the most important is the fuel flow transducer. By converting physical energy into an electrical signal, these devices can determine the rate at which fuel is being consumed and communicate that value to the pilot. As an essential instrument in a pilot’s display, it is very helpful for pilots and other aircraft operators to know what a fuel flow transducer is and how it works. In this blog, we will discuss these questions and more, delving deep into the mechanics of this crucial indicator device.

What Is a Fuel Flow Transducer?

At their core, transducers are devices which convert energy from one form to another. They come in two major types: input and output transducers. Input transducers are sensors which convert physical energy into a readable signal. A microphone is an example of an input transducer which takes sound waves and converts them into an electrical signal. Output transducers do the opposite, turning a signal into physical energy. One such example could be a speaker, because it reads the signal communicated by a microphone or recording and converts that electrical signal into sound waves. Fuel flow transducers are a type of input transducer which measures the physical movement of fuel and conveys it as a readable signal displaying flow rate. These types of transducers are commonly used in aircraft, where they measure the rate of flow of hydrocarbon jet fuel.

How Does It Work?

Fuel flow transducers work by converting the movement of fuel into an infrared light pattern which can then be interpreted into a signal for the pilot’s display. These transducers have a chamber for fuel to pass through on its way to the engine. On one side of the chamber is an infrared light emitter, and on the other is an infrared light receiver. Inside of this passage is a miniature neutrally buoyant rotor which can spin freely with the movement of the fuel. When an aircraft engine is running, an engine-driven pump draws fuel continuously through this flow chamber. As the fluid moves, it flows down a helical path and then exits vertically, releasing any vapor bubbles that may have been created during flow. The flowing fuel also spins the rotor so that it periodically cuts off the path of infrared light from the emitter to the detector. The pattern by which the infrared light is detected and blocked is directly proportional with the flow rate of the fuel. As such, the measurement of this rate can then be conveyed to the pilot as a measurement of the flow rate of fuel into the engine.


Fuel flow transducers are vital technology on aircraft which play a role in monitoring fuel consumption and management. By knowing the fuel flow rate aboard an aircraft, a pilot or engineer can monitor how much fuel they are using and take necessary steps to control the flow rate when necessary. Jet engines need a very precise flow rate of fuel to be mixed with air for combustion, so fuel flow transducers also make up a key factor in maintaining proper flight mechanics.

Hardware and Fasteners is here to assist you with all your aviation or aerospace part needs. We invite you to browse the catalog of available items on our website or use our easy-to-navigate search bar for more specific products of interest. To request a quote for your comparisons on any of the items we offer, simply send us a completed RFQ form available on our website, and a representative will reply with a custom competitive quote tailored to your specific needs in just 15 minutes!


Recent Twitter Posts

Semiconductor's Certifications and Memberships
The only independent
distributor with a
  • All orders are fulfilled in the USA.
  • All shipments must comply with U.S.A export laws.
  • No exceptions.
Fallen Heroes Fund

“We Proudly Support Intrepid Fallen Heroes Fund that serves United States Military Personal experiencing the Invisible Wounds of War : Traumatic Brain Injury (TBI) and Post Traumatic Stress (PTS). Please visit website ( and help in their valiant effort”.

Thank You for Visiting.

We Hope that You Will Visit Us Again the Next Time You Need NSN Parts and Make Us Your Strategic Purchasing Partner.

Request for Quote