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Common protective paint topcoats on aircraft

Aviation Mechanic General (AMG) practice question 27 of 36 on Cleaning and Corrosion Control. ACS element AM.I.G.K16 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONWhich finish is listed among the most common protective paint finishes applied to aircraft metal surfaces?

  1. ACatalyzed polyurethane enamel
  2. BNitrate dope over all metal skins
  3. CChromic acid inhibitor solution
Show the answer and explanation

Correct answer: A. Catalyzed polyurethane enamel

  • A — correct The most common protective paint finishes are catalyzed polyurethane enamel, waterborne polyurethane enamel, and two-part epoxy paint.
  • B — incorrect Nitrate and butyrate dope finishes are still available, but they are the finishes used for fabric-covered aircraft, not for metal skins.
  • C — incorrect A chromic acid solution is a chemical surface treatment and inhibitor used before refinishing; it is not a paint topcoat.

BACKGROUND

A good, intact paint finish is the most effective barrier between metal surfaces and corrosive media, so the topcoat system is a central part of corrosion control. The finishes most commonly used today are catalyzed polyurethane enamel, waterborne polyurethane enamel, and two-part epoxy paint. As regulations on the emission of volatile organic compounds (VOCs) have tightened, waterborne paint systems have grown in popularity. Nitrate and butyrate dope finishes remain available, but they belong to fabric-covered aircraft. Other specialized coatings exist as well, such as high-visibility fluorescent materials, rain erosion resistant coatings on metal leading edges, and baked enamel finishes on engine cases and wheels.

STUDY TIP

Learn the short list of common metal topcoats and keep dope finishes mentally filed under fabric covering, since that is the usual trap in this area.

KEY POINTS

  • The intact paint finish is the most effective barrier against corrosive media.
  • Common metal topcoats: catalyzed polyurethane enamel, waterborne polyurethane enamel, and two-part epoxy.
  • Nitrate and butyrate dopes are fabric-covering finishes, not metal topcoats.

SOURCES

  • FAA-H-8083-30B ch08 "Protective Paint Finishes"
Practice the Aviation Mechanic General (AMG) test →Timed 60-question exam, by ACS area, or review your misses. Free.
MORE ON CLEANING AND CORROSION CONTROL

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.