Definition
In a continuous-flow fuel injection system, the pressure differential across the air metering section of the fuel injection control unit that is used to meter the correct amount of fuel into the engine in proportion to the mass airflow being drawn in by the engine.
Plain English
It is a pressure difference created by the air flowing into the engine. The fuel injection system uses that pressure difference as a signal to know how much air the engine is breathing in, so it can deliver the right amount of fuel to match.
Context Anchor
Seen in aircraft carburetor and engine fuel-system discussions, especially when learning how a float-type carburetor mixes air and fuel.
Derivation
Meter here comes from the Greek 'metron,' meaning 'measure.' To 'meter' something is to measure and control the amount of it being delivered. So 'air metering force' is literally the force used to measure the airflow, which then governs how much fuel is metered out.
Why Pilots Care
Correct air metering force maintains the proper fuel-air ratio, preventing power loss, roughness, or engine damage from overly rich or lean mixtures.
Analogy
Like air being pulled through a drinking straw when pressure is lower in your mouth, air moves through the carburetor because pressure is lower inside the carburetor throat than at the inlet.
Grounding Statement
When the engine runs, it creates lower pressure inside the carburetor, and that pressure difference pulls air through.
Intuition Check
Force does not mean a separate mechanical part pushing the air. Here it means the effect of a pressure difference that makes air move.
Example Sentence 1
As the pilot opened the throttle, the increased airflow raised the air metering force, and the fuel injection system delivered more fuel to match.
Example Sentence 2
A partially blocked venturi reduces air metering force and can cause the engine to run lean at higher power settings.