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Wire separation from fluid lines

Aviation Mechanic Airframe (AMA) practice question 13 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.R3 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhen wiring must be routed near a line carrying flammable fluid, where should it run and with what separation?

  1. AAbove the line, at least 6 inches away
  2. BBelow the line, at least 6 inches away
  3. CAlongside the line, at least 2 inches away
Show the answer and explanation

Correct answer: A. Above the line, at least 6 inches away

  • A — correct Wiring must be routed above such lines and equipment with a minimum separation of 6 inches or more whenever possible.
  • B — incorrect Running the wire below the line would let leaking fluid fall onto it; the wire belongs above the line.
  • C — incorrect The 2-inch figure applies only where the preferred arrangement is impracticable, and wiring must then avoid running parallel to the line.

BACKGROUND

An arcing fault between an electrical wire and a metallic flammable fluid line may puncture the line and start a fire, so every effort must be made to physically separate wiring from lines and equipment carrying oxygen, oil, fuel, hydraulic fluid, or alcohol. Wiring must be routed above these lines and equipment with a minimum separation of 6 inches or more whenever possible. When that is not practicable, the wiring must be routed so that it does not run parallel to the fluid lines, and a minimum of 2 inches must be maintained. That 2-inch minimum may be reduced only where the wiring is positively clamped to maintain at least one half inch of separation, or where it must connect directly to fluid-carrying equipment. Clamps used for separation must not be relied on to support the wire bundle.

STUDY TIP

Learn the three distances as a ladder: 6 inches above is preferred, 2 inches is the fallback, and one half inch only with positive clamping.

KEY POINTS

  • Wiring is routed above flammable fluid lines, 6 inches or more away.
  • Where that is impracticable, keep 2 inches and avoid parallel runs.
  • One half inch is allowed only where the wire is positively clamped.

SOURCES

  • sources/ama-airframe/ch09.txt "Protection Against Solvents & Fluids"
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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.