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Installing aluminum terminal lugs

Aviation Mechanic Airframe (AMA) practice question 7 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.R6 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONHow should the tongue of an aluminum terminal lug be installed on a terminal stud?

  1. AWith a spacer between each tongue
  2. BDirectly against the stud's shoulder nut
  3. CSandwiched between two flat washers
Show the answer and explanation

Correct answer: C. Sandwiched between two flat washers

  • A — incorrect Spacers or washers should not be used between the tongues of terminal lugs.
  • B — incorrect This omits the required flat washers on either side of the aluminum tongue.
  • C — correct Aluminum terminal lug tongues, or the stack of tongues, should be sandwiched between two flat washers on the stud.

BACKGROUND

Aluminum terminal lugs should be crimped to aluminum wire only. The tongue of an aluminum terminal lug, or the total number of tongues when several are stacked, should be sandwiched between two flat washers when terminated on terminal studs. Spacers or washers should not be used between the tongues of terminal lugs. Aluminum wire and cable installations need special attention to guard against conditions producing excessive voltage drop and high resistance at junctions, which can eventually lead to failure of the junction. Examples of such conditions are improper installation of terminals and washers, improper torquing of nuts, and inadequate terminal contact areas.

STUDY TIP

Remember washers go outside the stack, never between tongues, and that aluminum lugs belong on aluminum wire only.

KEY POINTS

  • Aluminum lugs are crimped to aluminum wire only.
  • Aluminum tongues are sandwiched between two flat washers.
  • Nothing is placed between the tongues of stacked lugs.

SOURCES

  • sources/ama-airframe/ch09.txt "Aluminum Wire Terminals"
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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.