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Purity of 1130 wrought aluminum

Aviation Mechanic General (AMG) practice question 8 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K11 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONA piece of wrought aluminum stock is designated 1130. What is its minimum aluminum content?

  1. A99.13 percent pure aluminum
  2. B99.00 percent pure aluminum with 30 impurity controls
  3. C99.30 percent pure aluminum
Show the answer and explanation

Correct answer: C. 99.30 percent pure aluminum

  • A — incorrect The second digit (1) indicates the number of controls over individual impurities, not part of the purity figure; the purity comes from the last two digits, 30.
  • B — incorrect The last two digits add hundredths of a percent to the 99 percent base; they do not count impurity controls, which are shown by the second digit.
  • C — correct In the 1xxx group the last two digits give the hundredths of 1 percent above 99 percent, so 30 means 99 percent plus 0.30 percent, or 99.30 percent pure aluminum.

BACKGROUND

Wrought aluminum and wrought aluminum alloys are designated by a four-digit index system. The first digit identifies the alloy type, and a first digit of 1 means the metal is 99 percent aluminum or higher. In the 1xxx group, the second digit indicates the number of controls over individual impurities; zero means no special control. The last two digits indicate the hundredths of 1 percent above the original 99 percent. The handbook gives examples: 1100 is 99.00 percent pure aluminum with one control over individual impurities, 1130 is 99.30 percent with one control, and 1275 is 99.75 percent with two controls.

STUDY TIP

For 1xxx alloys, read the last two digits as hundredths added to 99 percent and the second digit as the count of impurity controls.

KEY POINTS

  • 1xxx alloys are 99 percent aluminum or higher.
  • The last two digits give hundredths of a percent above 99 percent.
  • 1130 is 99.30 percent pure aluminum with one impurity control.

SOURCES

  • FAA-H-8083-30B ch07 "Wrought Aluminum"
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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.