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Cause of cold laps and improper penetration

Aviation Mechanic General (AMG) practice question 36 of 36 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K13 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONA completed weld looks rough and irregular, its edges are not feathered into the base metal, and it shows cold laps and improper penetration. What produced this condition?

  1. AToo much heat or an oxidizing flame was used.
  2. BNot enough heat was applied to the joint.
  3. CThe filler rod was larger than required.
Show the answer and explanation

Correct answer: B. Not enough heat was applied to the joint.

  • A — incorrect Excessive heat or an oxidizing flame produces long, pointed ripples in a weld run too rapidly, not cold laps and shallow penetration.
  • B — correct Improper penetration and cold laps, along with a rough, irregular bead whose edges are not feathered into the base metal, are caused by insufficient heat.
  • C — incorrect Filler rod size does influence penetration, but the described combination of cold laps and unfeathered edges is attributed to insufficient heat.

BACKGROUND

Several patterns of unacceptable welds can be recognized by eye. A weld made too rapidly has long, pointed ripples caused by an excessive amount of heat or an oxidizing flame, and cross sectioning it would probably disclose gas pockets, porosity, and slag inclusions. A weld made with insufficient heat shows improper penetration and cold laps, appears rough and irregular, and its edges are not feathered into the base metal. Using an excessive amount of acetylene makes the puddle boil during welding, which often leaves slight bumps along the center of the bead and craters at the finish. A bad weld in general has irregular edges and considerable variation in the depth of penetration, and it often has the appearance of a cold weld.

STUDY TIP

Sort the visual defects by their cause: pointed ripples point to too much heat, cold laps point to too little, and boiling with bumps and craters points to excess acetylene. Read the described symptom carefully before choosing.

KEY POINTS

  • Cold laps and improper penetration come from insufficient heat.
  • Long, pointed ripples come from excessive heat or an oxidizing flame.
  • A bad weld shows irregular edges and considerable variation in penetration depth.

SOURCES

  • FAA-H-8083-30B ch10 "Inspection of Welds"
  • C:/Users/kuroh/faa-drill/sources/amg-general/ch10.txt (Inspection of Welds — examples of incorrect welds)
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.