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Why welds are never filed

Aviation Mechanic Airframe (AMA) practice question 5 of 20 on Metallic Structures. ACS element AM.II.A.K15 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhy should a completed weld never be filed to improve its appearance?

  1. AFiling removes part of the strength
  2. BFiling hardens the surface of the bead
  3. CFiling leaves scratches that trap moisture
Show the answer and explanation

Correct answer: A. Filing removes part of the strength

  • A — correct The handbook states plainly that filing a weld to give it a better appearance deprives the weld of part of its strength.
  • B — incorrect The objection stated in the handbook is loss of strength through metal removal, not any hardening effect.
  • C — incorrect Surface scratches are not the reason given; the prohibition rests on the strength taken out of the weld.

BACKGROUND

A completed weld should have an evenly rippled seam of uniform thickness, a slightly convex build-up that adds thickness at the joint, and a smooth taper into the base metal. No oxide should form on the base metal near the weld, there should be no blowholes, porosity, or projecting globules, and the base metal should show no burns, pits, cracks, or distortion. Appearance alone is not proof of quality, since a clean smooth weld may still be dangerously weak inside, though a weld that is rough, uneven, and pitted is almost always unsatisfactory internally. Because of that, welds are never filed to look better, as filing deprives the weld of part of its strength, and they are never filled with solder, brazing material, or filler of any sort. When a joint must be rewelded, all old weld material has to be removed first, and the mechanic should remember that reheating the area may leave the base metal weaker and brittle.

STUDY TIP

Learn the six characteristics of a good weld as a checklist, and remember that cosmetic fixes such as filing or filling are always prohibited.

KEY POINTS

  • Filing a weld to improve its appearance removes part of its strength.
  • Welds are never filled with solder, brazing material, or any filler.
  • Before rewelding a joint, all old weld material must be removed first.

SOURCES

  • sources/ama-airframe/ch05.txt "Characteristics of a Good Weld"
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MORE ON METALLIC STRUCTURES

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.