Pilot Exam Coach

US Private Pilot

Switch to Canada PSTAR
Aircraft systems and instrumentsQuestion 649 of 934

Why are the fuel tanks vented to the outside?

  1. To let the fuel cool in hot weather
  2. To drain water from the fuel into the sump
  3. To keep atmospheric pressure inside the tank
  4. To raise the fuel pressure at the engine pump
Show answer

Correct answer: To keep atmospheric pressure inside the tank

The vent may be in the filler cap or in a tube through the wing surface.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Fuel Systems — Fuel Tanks, page 186

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026