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Freezer storage of 2024-T4 rivets

Aviation Mechanic Airframe (AMA) practice question 15 of 20 on Metallic Structures. ACS element AM.II.A.K5 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhy are DD rivets made of 2024-T4 aluminum alloy stored in a freezer before they are installed?

  1. ATo prevent corrosion of the shank
  2. BTo retard hardening after annealing
  3. CTo keep the driven head from cracking later
Show the answer and explanation

Correct answer: B. To retard hardening after annealing

  • A — incorrect Cold storage is used to control the rate of hardening, not to protect the rivet from corrosive attack.
  • B — correct These rivets are too hard to drive as received, so they are annealed and then kept in a freezer to slow the hardening that would otherwise return before use.
  • C — incorrect The freezer addresses the condition of the rivet before driving; it is the hardness of the as-received alloy, not later head cracking, that makes the treatment necessary.

BACKGROUND

Aluminum alloys differ in how they gain their strength. Alloys such as 3003, 5052, and 1100 are hardened by cold working rather than by heat treatment, while 2017 and 2024 are hardened by heat treatment, cold working, or a combination of the two. That difference shows up directly in rivet handling. The most frequently used repair rivet is the AD rivet, alloy 2117, because it can be installed in the received condition and requires no heat treatment. DD rivets of alloy 2024-T4, by contrast, are too hard to drive as received and must be annealed first; they are then stored in a freezer to retard hardening, which earned them the nickname ice box rivets and requires that they be taken out only just before use. Most DD rivets have since been replaced by E-type rivets, which can be installed as received.

STUDY TIP

Tie each rivet alloy code to its driving condition: AD drives as received, DD must be annealed and chilled, and E-type replaced DD precisely to avoid that handling.

KEY POINTS

  • 2024-T4 DD rivets are too hard to drive as received and must be annealed.
  • Freezer storage retards hardening, giving them the name ice box rivets.
  • Alloy 2117 AD rivets need no heat treatment, which is why they dominate general repair work.

SOURCES

  • sources/ama-airframe/ch04.txt "Solid Shank Rivet"
  • sources/ama-airframe/ch04.txt "Aluminum Alloys"
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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.