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Aluminum-alloy nuts with cadmium-plated steel bolts

Aviation Mechanic General (AMG) practice question 13 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K9 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONUnder which condition may aluminum-alloy nuts be used with cadmium-plated steel bolts loaded in shear?

  1. AOn seaplanes only, where the bolts are plated
  2. BOn land airplanes only
  3. COn any aircraft, provided the bolts are torqued
Show the answer and explanation

Correct answer: B. On land airplanes only

  • A — incorrect The combination is specifically excluded on seaplanes due to the increased possibility of dissimilar metal corrosion.
  • B — correct Aluminum-alloy nuts may be used with cadmium-plated steel bolts loaded in shear on land airplanes, but not on seaplanes because of the increased possibility of dissimilar metal corrosion.
  • C — incorrect Torque does not address the dissimilar metal corrosion concern; the handbook restricts the combination to land airplanes.

BACKGROUND

The handbook places several restrictions on bolt and nut materials. Alloy-steel bolts smaller than No. 10-32 and aluminum-alloy bolts smaller than 1/4 inch in diameter are not used in primary structures. Aluminum-alloy bolts and nuts are not used where they are repeatedly removed for maintenance and inspection. Aluminum-alloy nuts may be used with cadmium-plated steel bolts loaded in shear on land airplanes, but are not used on seaplanes due to the increased possibility of dissimilar metal corrosion.

STUDY TIP

Link the seaplane exclusion to its reason, dissimilar metal corrosion in a wet, salty environment.

KEY POINTS

  • Aluminum-alloy nuts on cadmium-plated steel bolts in shear are acceptable on land airplanes.
  • They are not used on seaplanes because of dissimilar metal corrosion.
  • Aluminum-alloy hardware is avoided where repeatedly removed.

SOURCES

  • FAA-H-8083-30B ch07 "General Purpose Bolts"
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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.