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Support clamp spacing on a sensing element

Aviation Mechanic Airframe (AMA) practice question 7 of 9 on Airframe Fire Protection Systems. ACS element AM.II.M.K3 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONTypical practice locates the first support clamp about 4 to 6 inches from an end connector fitting and spaces clamps on straight runs about 8 to 10 inches apart. On a straight run, what is the greatest distance from the end connector fitting to the second clamp?

  1. A14 inches
  2. B20 inches, measured along the run
  3. C16 inches
Show the answer and explanation

Correct answer: C. 16 inches

  • A — incorrect This figure mixes the 6-inch first spacing with an 8-inch clamp spacing, which is the minimum rather than the maximum run spacing.
  • B — incorrect Twenty inches would require two full 10-inch clamp spacings and ignores the shorter 4 to 6 inch distance used at the end connector.
  • C — correct Taking the largest value allowed at each step, 6 inches to the first clamp plus 10 inches to the next clamp places the second clamp 16 inches from the fitting.

BACKGROUND

Continuous-loop sensing elements live in high-activity areas around engines, so routing and clamping are inspected closely. Long unsupported sections allow vibration that can break the element, which is why manufacturers specify clamp spacing, usually about 8 to 10 inches on straight runs. At end connectors the first support clamp is normally about 4 to 6 inches from the end connector fitting. A straight run of about one inch is kept from all connectors before a bend is started, and an optimum bend radius of about 3 inches is normally used. Grommets should be centered on their clamps with the split end facing the outside of the nearest bend.

STUDY TIP

Memorize the spacing numbers as a set (4 to 6 inches at the connector, 8 to 10 inches on the run, 1 inch straight before a bend, 3-inch bend radius) and be ready to add them for a scenario.

KEY POINTS

  • First clamp: about 4 to 6 inches from the end connector fitting.
  • Clamps on straight runs: about 8 to 10 inches apart.
  • Maximum values give 16 inches from the fitting to the second clamp.

SOURCES

  • sources/ama-airframe/ch17.txt "Fire Detection System Maintenance"
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MORE ON AIRFRAME FIRE PROTECTION 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.