SkyDrill

High rate of discharge system delivery time

Aviation Mechanic Powerplant (AMP) practice question 6 of 7 on Engine Fire Protection Systems. ACS element AM.III.E.K4 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONA high rate of discharge (HRD) fire extinguishing system delivers its quantity of extinguishing agent in approximately how much time?

  1. A10 to 15 seconds
  2. B30 to 45 seconds
  3. C1 to 2 seconds
Show the answer and explanation

Correct answer: C. 1 to 2 seconds

  • A — incorrect This is far longer than the HRD delivery time; the point of the design is a nearly instantaneous dump of agent.
  • B — incorrect The stated HRD delivery time is 1 to 2 seconds, so a figure measured in tens of seconds is much too long.
  • C — correct HRD systems use open-end tubes to deliver a quantity of extinguishing agent in 1 to 2 seconds.

BACKGROUND

Fixed extinguisher systems in engine fire protection dilute the atmosphere in the zone with an inert agent that does not support combustion. Many systems use perforated tubing or discharge nozzles to distribute the agent, while high rate of discharge (HRD) systems use open-end tubes to dump the charge in 1 to 2 seconds. The most common agent still in use is Halon 1301, chosen for its firefighting capability and relatively low toxicity; it is noncorrosive, does not affect the material it contacts, and requires no clean-up. Because Halon 1301 depletes the ozone layer, only recycled Halon 1301 is currently available while a replacement is developed. Carbon dioxide is also an effective agent and is most often found in extinguishers available on the ramp for fires on the exterior of the aircraft.

STUDY TIP

Tie the name to the number: "high rate of discharge" means the whole charge leaves in 1 to 2 seconds through open-end tubes. Contrast that with perforated tubing or nozzles used for distribution in other systems.

KEY POINTS

  • HRD systems use open-end tubes and discharge the agent in 1 to 2 seconds.
  • Fixed systems work by diluting the zone atmosphere with an inert agent.
  • Halon 1301 is the most common agent: effective, noncorrosive, and requiring no clean-up.

SOURCES

  • sources/amp-powerplant/ch09.txt "Fire Extinguishing Agents"
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON ENGINE FIRE PROTECTION SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.