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

How Do Fuel Injectors Work in an Aircraft?

Since their introduction as an upgrade to the carburetor in 1925, fuel injectors have become the default choice for modern gas-powered vehicles. Relying on either springs or an Electronic Control Unit, fuel injectors disperse a specific fuel-air mixture that is atomized to be used for quick, efficient combustion. Due to this capability, fuel injectors are crucial components on aircraft where precision is paramount. As such, it is important that pilots and engineers alike understand how these instruments work in order to best maintain them.

What Are Fuel Injectors?

Down to their core components, fuel injectors are electronically controlled valves which deliver a pressurized fuel-air mix to the engine. Whereas carburetors relied solely on the vacuum of the engine to distribute an indeterminate amount of gas, fuel injectors dispense an exact amount each time they are activated. Not only does the amount of gas being injected need to be accurate, but the angle it is placed at, the pressure, and the spray pattern all must be exact to meet the needs for the perfect air-to-fuel ratio for combustion. As such, fuel injector design can vary depending on the vehicle and type of gas being used. There are a number of different fuel injection systems available, but they can all be sorted into two main categories: mechanical fuel injection and electronic fuel injection.

How Do Mechanical Fuel Injection Systems Work?

Developed before their electronically controlled counterparts, mechanical fuel injection systems used mechanical devices to meter the correct amount of gas into the engine. Using a spring-loaded piston to open and close the valve, mechanical fuel injection systems are much more precise than carburetors. However, they still require tuning for optimal performance; therefore, they need more maintenance than electronic fuel injection systems. Mechanical fuel injection paved the way for modern Electronic Fuel Injection (EFI) systems which are controlled entirely by the Electronic Control Unit (ECU). As a result of their heightened control and precision, EFI is the preferred method used in today’s aircraft.

How Do Electronic Fuel Injectors Work?

Electronic Fuel Injectors allow for extremely precise control over the amount of fuel-air mixture that is delivered to the engine cylinders. The process follows these four steps:

  1. The gas exits the fuel tank by way of a pump and travels through the fuel line towards the engine.
  2. The fuel pressure regulator constricts the flow of gas and only lets a calculated amount through the injectors.
  3. The fuel pressure regulator is able to determine how much fuel to let through to the injectors because of a signal sent by the Mass Airflow Sensor (MAF). This sensor tracks how much air is entering the engine at any given time. The combination of this information, along with the optimal air/fuel ratio decided by the manufacturer, gives the ECU enough information to calculate the exact amount of fuel the engine needs.
  4. Finally, the fuel injectors themselves open to let the atomized gas directly into the combustion chamber.

Conclusion

Altogether, fuel injectors are a powerful system of valves which control the flow of a specific amount of gas and air to be ignited in the combustion chamber of a typical engine. In aircraft, these are always electronically driven to ensure a high level of accuracy and control. For access to an ever-expanding inventory of NSN, FSC, and aircraft parts, Internet of Hardware is here to assist you with all your parts procurement needs. We invite you to browse our inventory of available items on our website and submit a completed Request For Quote (RFQ) form to receive a competitive quote for your comparisons in just 15 minutes!


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