Definition
A component in a fuel injection system that meters fuel in proportion to airflow entering the engine, ensuring the correct fuel-to-air ratio is delivered to the fuel manifold for distribution to each cylinder. It receives air through the throttle body and fuel from the engine-driven fuel pump, then regulates fuel flow based on throttle position and engine demand.
Plain English
The part of a fuel-injected engine that decides how much fuel to send based on how much air the engine is taking in, so the mixture stays right.
Context Anchor
Seen in discussions of fuel-injection induction systems, especially when describing how fuel flow is controlled before it reaches the engine cylinders.
Why Pilots Care
Correct fuel-air proportion prevents power loss, overheating, and engine damage while maintaining efficient combustion.
Intuition Check
Do not assume the fuel-air control unit is simply a place where fuel and air are fully mixed. In this context, its main job is to regulate fuel flow so it matches the air going into the engine.
Example Sentence 1
On a fuel-injected aircraft, the fuel-air control unit adjusts fuel flow as the pilot advances the throttle for takeoff.
Example Sentence 2
During the run-up, the instructor demonstrated how the fuel-air control unit affects engine RPM when the mixture is adjusted.