Engine Fire Protection Systems

Question 1

What types of fire detector systems are used for engine fire detection ?

Answer 1

Overheat, rate of rise and flame detectors.

Question 2

How does a thermal switch fire protection system operate?

Answer 2

When heated past a predeterminant temperature, the switch closes the warning devices in the cockpit to activate.

Question 3

How many thermal switches are needed in a thermal switch fire protection system?

Answer 3

At least ONE.

Question 4

What kind of fire detection system allows more complete coverage than a spot-type system?

Answer 4

A continuous loop system.

Question 5

What happens in an engine equipped with a thermocouple fire warning system overheats slowly?

Answer 5

NOTHING… because a fast rise or rapid heating is required for this type of fire system to operate.

Question 6

What electrical power is required for a thermocouple fire protection system to operate?

Answer 6

BOTH… The thermocouple power and the aircraft electrical system are required.

Question 7

What is the likely cause of a false fire warning?

Answer 7

Fire sensing loop is bent or kinked.

Question 8

What are fire extinguishing systems designed to do?

Answer 8

They dilute the oxygen around the engine to a point that does not allow combustion or to reduce temperatures below the ignition point.

Question 9

Describe how a KIDDE and FENWAL continuos loop fire protection system functions:

Answer 9

KIDDLE – Inconel tube with two conductors, one grounded the other is a positive lead, when a fire or overheat occurs the resistance of the thermistor drops and allowing current to flow between the wires to activate the alarm.

FENWAL – Sensing element with ceramic beads, when a fire or overheat occurs the core resistance drops allowing current to flow between the center electrode and the ground to activate the alarm.

Question 10

What elements must be present for a fire to occur?

Answer 10

An ignition source, fuel and oxygen.

Question 11

What group of fire extinguishing agents are no longer manufactured after 1995?

Answer 11

Halons (or Freon or chlorofluorocarbons CFC).

Question 12

How are fire extinguishing agents distributed?

Answer 12

Through perforated tubing and/or discharge nozzles.

Question 13

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

Answer 13

The discharge cartridge, or squib, which is electrtrically ignited, fires a projectile into the frangible disk, thereby releasing fire extinguisher agent.

Question 14

How is a fire extinguisher system with a high rate of discharge classified?

Answer 14

As a HRD fire extinguisher system.

Question 15

How is an HRD fire extinguisher agent distributed?

Answer 15

Through open end tubes.

Question 16

How long does it take to discharge an HRD agent?

Answer 16

One to two seconds.

Question 17

How is the fire extinguishing agent in an HRD System distributed?

Answer 17

Through a series of high pressure tubes.

Question 18

What do the red and yellow discs in a fire extinguishing system indicate?

Answer 18

YELLOW – Normal discharge.

RED – Thermal discharge.

Question 19

What is the purpose of a pressure gauge in a fire extinguishing system?

Answer 19

Indicates pressure inside the container. To check if the pressure is within limits, a pressure temperature chart is used.

Question 20

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

Answer 20

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