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Disposition of suspected contaminated defueled fuel

Aviation Mechanic Airframe (AMA) practice question 2 of 12 on Aircraft Fuel Systems. ACS element AM.II.J.R4 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONA tank is defueled because its fuel is suspected of being contaminated. How must that fuel be handled?

  1. AStored separately from good fuel
  2. BReturned to the fuel truck for filtering
  3. CBlended with clean fuel of the same grade
Show the answer and explanation

Correct answer: A. Stored separately from good fuel

  • A — correct Fuel drained because of contamination or suspected contamination must not be mixed with any other fuel; it is stored in a separate container, treated if possible, or properly disposed of.
  • B — incorrect Putting it back in the truck mixes it with good fuel, which is exactly what must be prevented.
  • C — incorrect Blending spreads the contamination and risks placing it back aboard an aircraft.

BACKGROUND

Defueling may be required for maintenance, inspection, contamination, or a change in flight plan, and its safety procedures match those for fueling: work outside, have fire extinguishers on hand, and attach bonding cables to guard against static buildup. Tanks may have to be defueled in a prescribed sequence, just as they are fueled in one, to avoid structural damage. What happens to the removed fuel depends on its condition. Fuel drained because of known or suspected contamination is kept in a separate container from good fuel and is treated or disposed of properly, never placed back aboard an aircraft or mixed with good fuel. Good fuel that is defueled must go only into clean containers and must never be mixed with any other type of fuel; large aircraft can often transfer fuel between tanks and avoid defueling entirely.

STUDY TIP

Split defueling questions into two branches at once: what the procedure protects, and what happens to the fuel after it comes out.

KEY POINTS

  • Suspected contaminated fuel is stored separately, then treated or discarded.
  • Defueling safety matches fueling: outside, extinguishers, bonding cables.
  • Transferring fuel between tanks can avoid defueling on large aircraft.

SOURCES

  • sources/ama-airframe/ch14.txt, "Defueling"
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MORE ON AIRCRAFT FUEL SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.