SkyDrill

Chemical drier cartridge color indication

Aviation Mechanic Airframe (AMA) practice question 1 of 15 on Hydraulic and Pneumatic Systems. ACS element AM.II.F.K6 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONDuring servicing, a mechanic finds that the cartridge in a pneumatic system chemical drier is not blue. What does this indicate about the cartridge?

  1. AIt has reached its maximum pressure
  2. BIt is contaminated with moisture
  3. CIt is new and ready for service
Show the answer and explanation

Correct answer: B. It is contaminated with moisture

  • A — incorrect The cartridge color indicates moisture condition, not pressure; pressure limiting in a pneumatic system is the job of relief valves.
  • B — correct Each drier cartridge should be blue; if otherwise noted, the cartridge is to be considered contaminated with moisture and should be replaced.
  • C — incorrect Blue is the serviceable color, so any other color means the cartridge is not fit for continued service.

BACKGROUND

Pneumatic systems are protected against dirt by micronic and screen-type filters, and against moisture by moisture separators and chemical driers. The moisture separator is always located downstream of the compressor and removes moisture caused by the compressor. Chemical driers are incorporated at various locations in a pneumatic system, and their purpose is to absorb any moisture that may collect in the lines and other parts of the system. Each drier contains a cartridge that should be blue in color; if otherwise noted, the cartridge is to be considered contaminated with moisture and should be replaced.

STUDY TIP

Keep the two moisture devices straight: the separator sits downstream of the compressor and dumps collected water, while the drier cartridges absorb residual moisture and are judged serviceable by color.

KEY POINTS

  • A serviceable chemical drier cartridge is blue.
  • Any other cartridge color means moisture contamination and calls for replacement.
  • The moisture separator is always installed downstream of the compressor.

SOURCES

  • sources/ama-airframe/ch12.txt "Chemical Drier"
  • sources/ama-airframe/ch12.txt "Desiccant/Moisture Separator"
Practice the Aviation Mechanic Airframe (AMA) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON HYDRAULIC AND PNEUMATIC 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.