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Minimum tempering time by thickness

Aviation Mechanic General (AMG) practice question 28 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K2 · 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 hardened steel part is 3 inches thick. What is the minimum time it should be held at the tempering temperature?

  1. A3 hours
  2. B1 hour
  3. C4 hours, one for each inch plus one
Show the answer and explanation

Correct answer: A. 3 hours

  • A — correct The minimum tempering time is 1 hour, increased by 1 hour for each additional inch of thickness over one inch. A 3-inch part has 2 additional inches, so 1 + 2 = 3 hours.
  • B — incorrect One hour is the minimum for parts up to one inch thick. A part over one inch thick needs 1 additional hour for each additional inch.
  • C — incorrect The rule adds 1 hour only for each inch beyond the first inch, so a 3-inch part needs 3 hours, not 4.

BACKGROUND

Tempering reheats hardened steel to a temperature below the low critical point to reduce brittleness and produce definite physical properties. Approximate tempering temperatures for various tensile strengths are tabulated by steel number. The minimum time at the tempering temperature should be 1 hour. If the part is over one inch in thickness, the time is increased by 1 hour for each additional inch of thickness. The rate of cooling from the tempering temperature generally has no effect on the resulting structure, so the steel is usually cooled in still air.

STUDY TIP

Compute tempering time as 1 hour plus 1 hour for every inch of thickness beyond the first inch.

KEY POINTS

  • Minimum time at tempering temperature is 1 hour.
  • Add 1 hour for each additional inch of thickness over one inch.
  • After tempering, steel is usually cooled in still air.

SOURCES

  • FAA-H-8083-30B ch07 "Tempering"
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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.