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 KIDDLE 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