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High rate of discharge system delivery time

Aviation Mechanic Airframe (AMA) practice question 1 of 9 on Airframe Fire Protection Systems. ACS element AM.II.M.K6 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONIn a high rate of discharge (HRD) fire extinguishing system, how quickly is the quantity of extinguishing agent delivered?

  1. AIn 10 to 12 seconds
  2. BIn 1 to 2 seconds
  3. CIn 30 seconds or longer
Show the answer and explanation

Correct answer: B. In 1 to 2 seconds

  • A — incorrect This is far slower than the HRD design, whose whole purpose is a near-instantaneous dump of agent.
  • B — correct HRD systems use open-end tubes to deliver a quantity of extinguishing agent in 1 to 2 seconds.
  • C — incorrect A discharge this slow would not flood the zone quickly enough and does not describe an HRD system.

BACKGROUND

Fixed fire extinguishing systems in engine and cargo compartments work by diluting the atmosphere with an inert agent that does not support combustion. Many systems distribute the agent through perforated tubing or discharge nozzles, while high rate of discharge systems use open-end tubes instead. Halon 1301 remains the most common agent because of its firefighting capability and relatively low toxicity, and it is noncorrosive and leaves no residue to clean up. Agent is stored in containers, often called HRD bottles, that hold liquid agent under pressurized gas, typically nitrogen, and are usually made of stainless steel. Each container carries a temperature and pressure sensitive safety relief diaphragm to keep container pressure from exceeding test pressure if the bottle is exposed to excessive heat.

STUDY TIP

Associate "HRD" with open-end tubes and a 1 to 2 second dump, and contrast it with the perforated tubing and nozzles used by slower distribution systems.

KEY POINTS

  • HRD systems deliver the agent in 1 to 2 seconds through open-end tubes.
  • Halon 1301 is still the most common fixed-system agent.
  • HRD bottles store liquid agent under pressurized nitrogen.

SOURCES

  • sources/ama-airframe/ch17.txt "Halogenated Hydrocarbons Fire Extinguishing Systems"
  • sources/ama-airframe/ch17.txt "Containers"
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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.