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Where to cut a fabric test strip

Aviation Mechanic Airframe (AMA) practice question 7 of 30 on Non-Metallic Structures. ACS element AM.II.B.K14 · 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 a test strip is cut from an aircraft covering for a breaking strength test, from which area should the sample be taken?

  1. AA lower surface that is shaded from direct sunlight
  2. BAn inner surface near an inspection opening
  3. CAn upper surface with a dark colored finish
Show the answer and explanation

Correct answer: C. An upper surface with a dark colored finish

  • A — incorrect A shaded lower surface receives less ultraviolet exposure, so it would not represent the weakest fabric on the aircraft.
  • B — incorrect Fabric that is not exposed to the elements does not show the deterioration the test is meant to find.
  • C — correct The sample should come from an area exposed to the elements, usually an upper surface, and from a dark colored finish because it absorbs more ultraviolet radiation and degrades faster.

BACKGROUND

Ultraviolet radiation is the only significant cause of deterioration of polyester covering fabric, so the most degraded fabric is where the sun strikes hardest. The approved test strip method calls for cutting a strip one and one-quarter inches by four to six inches from the covering. The handbook directs that the sample be taken from an area exposed to the elements, usually an upper surface, and adds that it is wise to choose an area with a dark colored finish because it has absorbed more ultraviolet rays and degraded faster. All coatings must be removed from the strip before testing, which is usually done by soaking and cleaning it in methyl ethyl ketone. The edges are then raveled to leave a one-inch width for the test.

STUDY TIP

Think about where the fabric is weakest rather than where it is convenient to cut, and remember that dark finishes on upper surfaces deteriorate first.

KEY POINTS

  • Take the test strip from an area exposed to the elements.
  • Upper surfaces with dark finishes degrade fastest.
  • Remove all coatings from the strip before testing.

SOURCES

  • FAA-H-8083-31B ch03 "How Fabric Breaking Strength is Determined"
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MORE ON NON-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.