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Wire routing near flammable fluid lines

Aviation Mechanic Powerplant (AMP) practice question 3 of 13 on Engine Electrical Systems. ACS element AM.III.F.R3 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONA wire bundle must be routed for a short distance parallel to a plumbing line that carries flammable fluid. What does the handbook require?

  1. AKeep the wire at least 1/2 inch from the line.
  2. BRoute the wire below the line at any spacing.
  3. CSupport the wire bundle from the plumbing line.
Show the answer and explanation

Correct answer: A. Keep the wire at least 1/2 inch from the line.

  • A — correct No wire should be routed nearer than 1/2 inch to a plumbing line, and as much separation as possible should be maintained when the run is parallel to a combustible fluid or oxygen line.
  • B — incorrect Wires should be on a level with, or above, the plumbing lines, so that fluid leaking from the line does not run onto the wiring.
  • C — incorrect A wire or wire bundle must never be supported from a plumbing line that carries flammable fluids or oxygen.

BACKGROUND

When wiring must be routed parallel to combustible fluid or oxygen lines for short distances, as much separation as possible should be maintained, and the wires should be on a level with or above the plumbing lines. Clamps are spaced so that a wire broken at a clamp cannot contact the line. Where a 6-inch separation is not possible, the wire bundle and the plumbing line may be clamped to the same structure to prevent relative motion; if the separation is less than 2 inches but more than 1/2 inch, two cable clamps back to back may be used to hold a rigid separation, but not to support the bundle. No wire may be routed nearer than 1/2 inch to a plumbing line, and no wire or bundle may be supported from a line carrying flammable fluids or oxygen. Wiring is also kept at least 3 inches clear of control cables, or mechanical guards are installed.

STUDY TIP

Memorize the three distances in this paragraph, 6 inches, 2 inches and 1/2 inch, and the rule that wires ride level with or above the plumbing.

KEY POINTS

  • Keep wires level with or above flammable fluid lines.
  • Never route a wire closer than 1/2 inch to a plumbing line.
  • Never support a bundle from a line carrying flammable fluid or oxygen.

SOURCES

  • amp-powerplant/ch04.txt "Routing Precautions"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.