Definition
Small open tubes that connect a fuel tank to outside air, allowing air to enter as fuel is drawn out so the tank pressure stays equal to outside atmospheric pressure.
Plain English
Little air pipes on the fuel tank. As fuel leaves the tank, air comes in through these tubes to replace it, so the tank does not collapse or starve the engine of fuel.
Context Anchor
A pilot encounters fuel vent tubes during fuel system study and during preflight inspection, where vents should be checked for blockage, ice, dirt, or insect nests.
Derivation
Vent' comes from the Latin ventus, meaning wind or air. A vent tube is simply a tube that lets air pass, so the tank can breathe.
Why Pilots Care
Blocked vent tubes can create a vacuum that stops fuel flow, causing engine failure even when tanks contain usable fuel.
Analogy
Think of drinking from a juice box. If you suck hard with no air getting in, the box collapses and the juice stops flowing. A small hole or straw lets air in so the liquid keeps coming out smoothly. Fuel vent tubes do the same job for the fuel tank.
Intuition Check
Do not think of fuel vent tubes as tubes that feed fuel to the engine. Their main purpose is to let air and pressure move in or out of the fuel tank so fuel can keep flowing properly.
Example Sentence 1
During preflight, the pilot checked that the fuel vent tubes under each wing were clear and not plugged with insects.
Example Sentence 2
A clogged vent tube on one tank caused fuel starvation during a prolonged climb.