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Aircraft systems and instrumentsQuestion 650 of 934

A pilot fills the tanks on a hot day and sees fuel coming from the overflow drain. What does this mean?

  1. It is not unusual; fuel expands as it warms
  2. The tank is cracked and must be replaced
  3. The fuel selector is in the wrong position
  4. The fuel contains water and must be drained
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Correct answer: It is not unusual; fuel expands as it warms

The overflow drain lets fuel expand with an increase in temperature without damage to the tank.

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