Definition
A tapered pin that moves inside a fuel-metering jet or orifice in a carburetor or fuel control unit. As the pin moves in or out of the orifice, it changes the size of the opening and therefore the amount of fuel that can flow through it. Metering pins are commonly linked to the throttle or to a power-control mechanism so that fuel flow varies correctly with engine power demand.
Plain English
A shaped pin that slides in and out of a small fuel hole to control how much fuel gets through. Push the pin in further and less fuel flows; pull it out and more fuel flows.
Context Anchor
Seen in aircraft fuel-system and carburetor discussions, especially when describing how fuel flow is controlled inside the unit.
Derivation
Metering' comes from 'meter,' meaning to measure or regulate an amount. The pin meters fuel — it regulates how much passes through the opening. Knowing this makes the part's job obvious from its name.
Why Pilots Care
Controls strut damping to prevent excessive bounce or bottoming on landing and reduces wear on the gear structure.
Analogy
Think of a metering pin like the tapered stopper in a sink drain, except it controls fuel instead of water. Moving it changes how much opening is available for flow.
Intuition Check
Do not think of this as a simple fastening pin. In this context, the pin is a moving control part that changes fuel flow.
Example Sentence 1
When the throttle is advanced, the metering pin lifts out of the jet and allows more fuel to reach the engine.
Example Sentence 2
A scored metering pin allowed too much fluid to pass, causing the airplane to rebound hard after touchdown.