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Class D powerplant fire zone

Aviation Mechanic Airframe (AMA) practice question 5 of 9 on Airframe Fire Protection Systems. ACS element AM.II.M.K1 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONPowerplant compartments are classified into fire zones by the airflow through them. Which zone is an area of very little or no airflow?

  1. AClass D zone, such as a wheel well
  2. BClass B zone, such as a heat exchanger duct
  3. CClass C zone, such as an accessory compartment
Show the answer and explanation

Correct answer: A. Class D zone, such as a wheel well

  • A — correct A Class D zone is an area of very little or no airflow, and wing compartments and wheel wells, where little ventilation is provided, are the examples given.
  • B — incorrect A Class B zone is an area of heavy airflow past aerodynamically clean obstructions, and heat exchanger ducts are listed as that type, not as a low-airflow area.
  • C — incorrect A Class C zone is an area of relatively low airflow, not of very little or no airflow; an engine accessory compartment separated from the power section is the example used.

BACKGROUND

Fire zone classification tells the designer and the mechanic how much extinguishing agent a compartment needs and how the agent will behave once it is released. A Class A zone has heavy airflow past regular arrangements of similarly shaped obstructions, such as the power section of a reciprocating engine. A Class B zone also has heavy airflow, but past aerodynamically clean obstructions such as heat exchanger ducts and exhaust manifold shrouds. A Class C zone has relatively low airflow, and a Class D zone has very little or no airflow, which is why wing compartments and wheel wells fall in that group. A Class X zone combines heavy airflow with unusual construction, and tests indicate its agent requirement is double that of a Class A zone.

STUDY TIP

Learn the five zone classes by the amount of airflow first and the example compartment second; the examples are what most questions key on.

KEY POINTS

  • Zones are classified by the airflow through the compartment.
  • Class D means very little or no airflow: wing compartments and wheel wells.
  • Class X needs double the agent required for a Class A zone.

SOURCES

  • sources/ama-airframe/ch17.txt "Fire Zones"
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MORE ON AIRFRAME FIRE PROTECTION 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.