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Cleaning agents unsafe for LCD screens

Aviation Mechanic Airframe (AMA) practice question 6 of 20 on Aircraft Instrument Systems. ACS element AM.II.H.K12 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhich cleaning agent must be avoided on a liquid crystal display screen that has an antireflective coating?

  1. ACleaners containing ammonia.
  2. BCleaners approved for coated lenses.
  3. CA clean, lint-free cloth.
Show the answer and explanation

Correct answer: A. Cleaners containing ammonia.

  • A — correct Antireflective treatments can be degraded by human skin oils and by certain cleaning agents, such as those containing ammonia.
  • B — incorrect A cleaner specified as safe for antireflective coatings is exactly what the handbook recommends using.
  • C — incorrect A clean, lint-free cloth is the recommended means of wiping the display lens, so it is not something to avoid.

BACKGROUND

Electronic and digital instrument systems that use liquid crystal display, or LCD, technology need special care of the display screens themselves. Antireflective coatings are sometimes applied to reduce glare and make the displays easier to read in bright flight deck conditions. These coatings are fragile chemically: they can be degraded by human skin oils and by certain cleaning agents, particularly those containing ammonia. The correct method is to clean the display lens with a clean, lint-free cloth using a cleaner specified as safe for antireflective coatings, preferably one recommended by the aircraft manufacturer. Because a degraded coating cannot be restored in the field, avoiding the wrong cleaner is far cheaper than replacing the display unit.

STUDY TIP

Whenever a question involves a coated display, look for the answer that points to a manufacturer-approved cleaner and a lint-free cloth.

KEY POINTS

  • Antireflective coatings on LCD screens are damaged by skin oils and ammonia-based cleaners.
  • Use a clean, lint-free cloth with a cleaner specified as safe for the coating.
  • The manufacturer's recommended cleaner is the preferred choice.

SOURCES

  • sources/ama-airframe/ch10.txt "LCD Display Screens"
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MORE ON AIRCRAFT INSTRUMENT SYSTEMS

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.