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Wire support interval

Aviation Mechanic Airframe (AMA) practice question 14 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.R4 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONExcept where contained in troughs, ducts, or conduits, at what maximum interval must wires and cables be supported?

  1. AEvery 36 inches
  2. BEvery 12 inches, without exception
  3. CEvery 24 inches
Show the answer and explanation

Correct answer: C. Every 24 inches

  • A — incorrect This exceeds the stated maximum interval between supports.
  • B — incorrect The interval is not this short, and troughs, ducts, and conduits are an allowed exception.
  • C — correct Wires and cables are supported by clamps, grommets, or other devices at intervals of not more than 24 inches.

BACKGROUND

Wire and cable clamps must be inspected for proper tightness, and where cables pass through structure or bulkheads the clamping and grommets must be checked. There must be enough slack between the last clamp and the electronic equipment to prevent strain at the cable terminals and to limit adverse effects on shock-mounted equipment. Wires and cables are supported by suitable clamps, grommets, or other devices at intervals of not more than 24 inches, except when contained in troughs, ducts, or conduits. The supporting devices must hold the wires securely without damaging the insulation. Metal stand-offs are used to maintain clearance between wires and structure, and tape or tubing is not an acceptable substitute for stand-offs.

STUDY TIP

Pair the 24-inch support interval with the one half inch maximum bundle deflection between supports; both describe how tightly a bundle is controlled.

KEY POINTS

  • Supports are spaced no more than 24 inches apart.
  • Troughs, ducts, and conduits are the exception to that spacing.
  • Tape or tubing may not replace metal stand-offs for clearance.

SOURCES

  • sources/ama-airframe/ch09.txt "Wire & Cable Clamp Inspection"
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MORE ON AIRCRAFT ELECTRICAL SYSTEMS

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.