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Restoring a cracked dope finish

Aviation Mechanic Airframe (AMA) practice question 23 of 30 on Non-Metallic Structures. ACS element AM.II.B.K15 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONThe dope coatings on a fabric covering have developed cracks, but field testing shows the fabric underneath is still airworthy. What product may be applied per the manufacturer's instructions?

  1. AA rejuvenator
  2. BAn additional sealer coat
  3. CAn acid etch and fresh primer
Show the answer and explanation

Correct answer: A. A rejuvenator

  • A — correct A rejuvenator is sprayed on to soften the coatings with powerful solvents, and its plasticizers become part of the film and fill in the cracks.
  • B — incorrect A sealer coat is applied over new fabric during the covering process and does not restore a cracked dope film.
  • C — incorrect Acid etching and priming prepare bare metal structure before covering and are not used on an existing dope finish.

BACKGROUND

Cracks in dope coatings can expose the fabric beneath to the elements and weaken it, so close observation and field testing are used to decide whether the fabric is still airworthy. If the fabric is not airworthy, the aircraft must be re-covered. If the fabric is airworthy and no other problems exist, a rejuvenator can be used according to the manufacturer's instructions. It is usually sprayed on, softens the coatings with very powerful solvents, and its plasticizers become part of the film that fills in the cracks. After the rejuvenator dries, additional coats of aluminum-pigmented dope are added, followed by the final topcoats. Polyurethane-based finishes cannot be rejuvenated.

STUDY TIP

Rejuvenation only buys time on a dope system and only when the fabric itself still passes. Note the limitation that polyurethane-based finishes cannot be rejuvenated at all.

KEY POINTS

  • A rejuvenator softens cracked dope and fills the cracks with plasticizers.
  • Aluminum-pigmented dope and topcoats are reapplied after it dries.
  • Polyurethane-based finishes cannot be rejuvenated.

SOURCES

  • ama-airframe/ch03.txt "Determining Fabric Condition—Repair or Recover?"
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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.