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Dents and kinks in a sensing element

Aviation Mechanic Powerplant (AMP) practice question 5 of 7 on Engine Fire Protection Systems. ACS element AM.III.E.K3 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONDuring inspection, a mechanic finds a dent in a continuous-loop sensing element that is within the manufacturer's acceptable limits. What is the correct action?

  1. ALeave the dent as it is and return the element to service
  2. BCarefully straighten the dent before returning it to service
  3. CReplace the element because all dents are cause for removal
Show the answer and explanation

Correct answer: A. Leave the dent as it is and return the element to service

  • A — correct No attempt should be made to straighten an acceptable dent or kink, because straightening can set up stresses that could cause tubing failure.
  • B — incorrect Straightening is specifically prohibited; the stresses it creates could cause the tubing to fail later.
  • C — incorrect The manufacturer specifies acceptable limits on dents and kinks, so a dent within those limits does not by itself require replacement.

BACKGROUND

Fire detector sensing elements sit in high-activity areas around engines, and their small size makes them easy to damage during maintenance. A visual inspection program for continuous-loop systems looks for cracked or broken sections from crushing, abrasion from rubbing on cowling or structure, metal particles that could short terminals, and the condition of the rubber grommets in the mounting clamps. Dents and kinks are also inspected, and limits on element diameter, acceptable dents and kinks, and smoothness of the tubing contour are specified by the manufacturer. An acceptable dent or kink must be left alone, because straightening can set up stresses that could cause tubing failure. Routing and clamping are checked as well, since long unsupported sections can vibrate and break.

STUDY TIP

Remember that "within limits" means leave it alone, not fix it: the handbook forbids straightening any acceptable dent or kink. Always compare what you find against the manufacturer's stated limits rather than your own judgment.

KEY POINTS

  • Manufacturers publish limits for dents, kinks, diameter, and tubing contour on sensing elements.
  • An acceptable dent or kink is never straightened, because induced stresses can cause tubing failure.
  • Inspections also cover cracks, abrasion, metal particles, grommet condition, and clamping.

SOURCES

  • sources/amp-powerplant/ch09.txt "Fire Detection System Maintenance"
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MORE ON ENGINE FIRE PROTECTION SYSTEMS

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.