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Weight of magnesium compared with aluminum

Aviation Mechanic General (AMG) practice question 1 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K1 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONMagnesium, the world's lightest structural metal, weighs approximately how much in comparison with aluminum?

  1. AAbout 18 percent less than aluminum
  2. BAbout two-thirds as much
  3. CAbout one-half as much
Show the answer and explanation

Correct answer: B. About two-thirds as much

  • A — incorrect The 18 percent figure is the weight saving quoted for wing panels made entirely of magnesium alloy compared with aluminum panels, not the density ratio of the metals themselves.
  • B — correct The handbook describes magnesium as a silvery white material weighing only two-thirds as much as aluminum.
  • C — incorrect Magnesium weighs two-thirds as much as aluminum, not half; one-half would overstate the weight saving.

BACKGROUND

Magnesium is the world's lightest structural metal, a silvery white material weighing only two-thirds as much as aluminum. In its pure state it lacks the strength for structural use, but alloyed with zinc, aluminum, and manganese it produces an alloy with the highest strength-to-weight ratio of any commonly used metal. Wing panels fabricated entirely from magnesium alloys weigh about 18 percent less than standard aluminum panels. Magnesium is used for parts such as nosewheel doors, flap cover skins, oil tanks, floorings, wingtips, and instrument panels.

STUDY TIP

Keep the two magnesium numbers separate: two-thirds is the weight of the metal relative to aluminum, while 18 percent is the saving on a finished wing panel.

KEY POINTS

  • Magnesium is the lightest structural metal.
  • It weighs about two-thirds as much as aluminum.
  • Alloyed magnesium has the highest strength-to-weight ratio of common metals.

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.