FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationEasy
A mechanic is inspecting the fuel tank venting system on an aircraft. What is the primary function of a properly operating fuel tank vent?
- ATo prevent fuel spillage during aggressive maneuvers.
- BTo allow air to enter and exit the tank to prevent pressure differentials.
- CTo provide an overflow path for excess fuel during refueling.
- DTo filter contaminants from the air entering the fuel tank.
Show answer & explanationAnswer & explanation
Correct answer: B. To allow air to enter and exit the tank to prevent pressure differentials.
A fuel tank vent's primary function is to equalize pressure between the inside of the fuel tank and the outside atmosphere. This prevents a vacuum from forming as fuel is consumed (leading to fuel starvation) and prevents over-pressurization during temperature changes or refueling.
Why the other options are wrong
- A. Anti-spill features are part of tank design or filler caps, not the primary role of the vent.
- C. Overflow is typically handled by separate overflow drains, though some vents might serve a dual purpose, it's not their primary function.
- D. While some vents may have screens, their primary role is pressure equalization, not filtration.
Fuel Tank Venting
A system that allows air to freely enter and exit the fuel tank, preventing pressure differentials that could lead to tank collapse, rupture, or fuel starvation.
- Prevents vacuum as fuel is consumed.
- Prevents over-pressurization from temperature changes.
- Ensures consistent fuel flow to the engine.
Memory trick: Vent is the 'breather' for the tank, keeping pressure balanced.