Engine Fire Protection Systems

Question 1

Name at least two types of fire detector systems used for engine fire protection.

Answer 1

(1) Overheat; (2) Rate-of-temperature-rise; (3) Flame detectors

Question 2

What is the minimum number of thermal switch units needed for a thermal switch fire protection system?

Answer 2

At least one.

Question 3

Name the type of fire detection system that permits more complete coverage of an area than spot-type detectors?

Answer 3

A continuous loop system.

Question 4

Describe the principle of a Kidde continuous loop fire protection system?

Answer 4

Two wires are imbedded in a special ceramic core within an inconel tube. One wire is a ground and the second wire is a hot lead that provides a current when the ceramic core material changes it’s resistance due to temperature.

Question 5

What is the principle of operation in a Fenwall continuous loop fire protection system?

Answer 5

A single nickel wire is surrounded by eutectic salt in an inconel tube. The resistance is sharply lowered with temperature rise.

Question 6

What is the purpose of a fire extinguishing system?

Answer 6

To dilute the atmosphere around a fire with an inert agent that will not support combustion.

Question 7

What are two methods used to distribute fire extinguishing agents?

Answer 7

Perforated tubing and/or discharge nozzles.

Question 8

What is an HRD fire extinguisher system?

Answer 8

A fire extinguisher system with a high rate of discharge.

Question 9

How is an HRD fire extinguisher agent distributed?

Answer 9

Open end tubes.

Question 10

How long does it take to discharge an HRD agent?

Answer 10

One to two seconds.

Question 11

What are the red and yellow disks associated with a fire extinguisher system used to indicate?

Answer 11

Red indicates a thermal discharge and yellow indicates a normal discharge.

Question 12

What is likely to happen when an engine fire sensing loop is excessively kinked or bent?

Answer 12

A false fire warning.

Question 13

What indicates low agent pressure in a container and a fire extinguisher system?

Answer 13

A pressure gauge.

Question 14

What is the proper method for determining the fire extinguisher container pressure?

Answer 14

Container gauge pressure used with a pressure-temperature curve/chart will indicate if the pressure is within limits.

Question 15

What are the essential ingredients necessary for any fire to occur?

Answer 15

Heat (or ignition source), fuel, and oxygen.

Question 16

What happens to a thermal switch fire protection system when it is heated enough to operate?

Answer 16

Switch contacts close and provide a ground for the cockpit fire warning devices.

Question 17

What will happen in a thermocouple fire warning system on an engine that overheats slowly?

Answer 17

Nothing, because it takes a fast rate of rise or rapid heating to operate.

Question 18

What electrical power is needed for a thermocouple fire protection system?

Answer 18

The aircraft electrical system and thermocouple produced voltage.

Question 19

What is the purpose of a discharge cartridge and how it is activated?

Answer 19

The electrically operated discharge cartridge releases the fire extinguishing agent.

Question 20

What group of fire extinguishing agents are no longer being manufactured because of environmental concerns and are subject to strict handling and disposal regulations?

Answer 20

Halons (or freon or chlorofluorocarbons (CFCs)).