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Class I flammable liquids in cleaning work

Aviation Mechanic General (AMG) practice question 28 of 36 on Cleaning and Corrosion Control. ACS element AM.I.G.R4 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONClass I flammable liquids, which are not to be used for aircraft cleaning or refurbishing, are those having which characteristic?

  1. AA flash point of 100 °F or more
  2. BA flash point between 100 °F and 140 °F
  3. CA flash point below 100 °F
Show the answer and explanation

Correct answer: C. A flash point below 100 °F

  • A — incorrect Liquids at or above 100 °F are the high flash point materials that may be used when a flammable liquid is absolutely necessary.
  • B — incorrect That range describes the stable high flash point petroleum solvents, which are the acceptable choice rather than the prohibited one.
  • C — correct Class I flammable liquids are defined by a flash point below 100 °F, and these are not to be used for aircraft cleaning or refurbishing.

BACKGROUND

Cleaning agents are grouped by fire hazard, and flash point is the dividing line. Class I flammable liquids have a flash point below 100 °F and are not to be used for aircraft cleaning or refurbishing; acetone, aviation gasoline (AVGAS), methyl ethyl ketone, naphtha, and toluol fall in this class. Where it is absolutely necessary to use a flammable liquid, high flash point liquids with a flash point of 100 °F or more are used instead. Specially refined petroleum products of the Stoddard solvent type are typically stable, with a flash point from 100 °F to 140 °F and a comparatively low degree of toxicity. Solvent cleaners used in aircraft cleaning should have a flash point of not less than 105 °F if explosion proofing of equipment and other special precautions are to be avoided.

STUDY TIP

Fix 100 °F as the Class I dividing line and 105 °F as the practical minimum for solvent cleaners, then check any solvent's label and Safety Data Sheet against those numbers.

KEY POINTS

  • Class I flammable liquids have a flash point below 100 °F and are not used for aircraft cleaning.
  • If a flammable liquid is unavoidable, use one with a flash point of 100 °F or more.
  • Solvent cleaners should have a flash point of not less than 105 °F to avoid special precautions.

SOURCES

  • FAA-H-8083-30B ch08 "Flammable & Combustible Agents"
  • FAA-H-8083-30B ch08 "Solvent Cleaners"
Practice the Aviation Mechanic General (AMG) test →Timed 60-question exam, by ACS area, or review your misses. Free.
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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.