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Extinguishing a magnesium chip fire

Aviation Mechanic General (AMG) practice question 2 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K1 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONWhile machining a magnesium alloy part, a mechanic sees a pile of fine magnesium chips ignite. What should be used to extinguish the fire?

  1. AA dry extinguishing powder such as soapstone or graphite
  2. BA standard foam fire extinguisher, applied at the base of the fire
  3. CA stream of water to cool the chips below their ignition point
Show the answer and explanation

Correct answer: A. A dry extinguishing powder such as soapstone or graphite

  • A — correct The handbook states that a magnesium fire could be extinguished with an extinguishing powder, such as soapstone or graphite.
  • B — incorrect Water or any standard liquid or foam fire extinguisher causes magnesium to burn more rapidly and can cause explosions.
  • C — incorrect Water causes magnesium to burn more rapidly and can cause explosions; it must not be used on a magnesium fire.

BACKGROUND

Magnesium embodies fire hazards of an unpredictable nature. In large sections its high thermal conductivity makes it difficult to ignite, and it does not burn until its melting point of 1,204 °F is reached. Magnesium dust and fine chips, however, are ignited easily, so precautions must be taken when machining or grinding the metal. Should a fire occur, it can be extinguished with an extinguishing powder such as soapstone or graphite. Water or any standard liquid or foam extinguisher causes magnesium to burn more rapidly and can cause explosions.

STUDY TIP

Remember that fine magnesium chips ignite easily and that only a dry powder is acceptable; water and foam make the fire worse.

KEY POINTS

  • Magnesium dust and fine chips ignite easily.
  • Extinguish a magnesium fire with a powder such as soapstone or graphite.
  • Water and foam extinguishers make magnesium burn faster and can cause explosions.

SOURCES

  • FAA-H-8083-30B ch07 "Magnesium & Magnesium Alloys"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.