11.8

Question 1

What is a fire zone?

Answer 1

An area requiring detection and/or fire extinguishing equipment as well as high level of fire resistance

Question 2

Which areas are fire zones?

Answer 2

-APU
-baggage/ cargo
-lavatories
-electrical/ electronic equipment compartments
-wheel wells
-bleed air ducts

Question 3

What fire detectors are more common in turbo prop/ reciprocating engines?

Answer 3

-overheat detectors
-rate of temp rise detectors
-flame detectors
-observation by crew members

Question 4

What fire protection systems are on large turbine aircraft?

Answer 4

-Rate of temp rise detectors
-radiation sensing detectors
-smoke detectors
-overheat detectors
-carbon monoxide detectors
-combustible mixture detectors
-optical detectors
-observation

Question 5

Where are overheat warnings?

Answer 5

Areas of high temperatures that may lead to a fire

Question 6

What are the most common sensing devices?

Answer 6

-thermal switches
-thermocouples
-continuing loop sensing elements

Question 7

How does a thermal switch system work?

Answer 7

Lights operated by a thermocouple

Question 8

What is a continuous loop system?

Answer 8

Used on large commercial aircraft
The common types:
-thermistor kindle/fenwell
-pneumatic pressure Lingberg/ meggit

Question 9

What is the fenwell system?

Answer 9

An inconel tube with a thermally sensitive eutectoid salt and a nickel wire centre conductor

A small current is passed through this and can drop in resistance when exposed to high temperatures

A conductive path is established

Question 10

How does a kiddle system differ?

Answer 10

There are two wires imbedded

Question 11

What is a dual loop system?

Answer 11

It diminishes the chance of of a false reading by creating a system where both have to read that there is a fire

Question 12

What is a pneumatic continuous loop system?

Answer 12

Operates on a principle of a contained gas expanding due to heat exposure
Used in:

-engine overheat
-fire detection on commercial aircraft

Question 13

What are the two sensing functions of a pneumatic continuous loop system?

Answer 13

-the overall average temperature threshold
-detecting localised discrete temperature increase that is caused by flames or gas

Question 14

How does the overall average temperature sensing function work?

Answer 14

-measured expansion of contained helium

Question 15

How does the discrete temperature sensing function work on pneumatic close loop systems?

Answer 15

-hydrogen filled core
-hydrogen is released when a small section of the tube is heated to a pre set temperature for 5 seconds
-the sensing function is reversible

Question 16

What are common faults with fire detection systems?

Answer 16

-intermittent alarm is caused by and intermittent short
-it can sound with no fire
-sharp bends can cause shorts
-moisture Less commonly

Question 17

What are the two basic types of smoke detectors?

Answer 17

-photo electric
-ionisation

Question 18

How does a refraction photo electric system function?

Answer 18

Smoke causes refraction

Question 19

How does an ionisation type smoke detector function?

Answer 19

-there is a very small amount of radioactive material on one side
-the electrode opposite detects ionised nitrogen and oxygen smoke reduces this

Question 20

What type of detector is used in cargo bays?

Answer 20

Optical

Question 21

How does an optical smoke detector function?

Answer 21

-An LED sends out light
-air is sucked into the detector
-smoke effects the light refraction

Question 22

When must a lavatory smoke detector be installed?

Answer 22

When there are 20 or more passengers

Question 23

What are the fire zones?

Answer 23

-engines
-APU
-baggage / cargo
-lavatories

Question 24

What must be done by a fire detection system?

Answer 24

Rapidly detect fire but not necessarily deploy the extinguisher

Question 25

What is the most common extinguisher on board an aircraft?

Answer 25

Halon 1301

Question 26

What are the characteristics of fire extinguisher bottles?

Answer 26

-Liquid halogen pressurised by nitrogen -temperature/ pressure relief diagram -it contains a discharge valve

Question 27

What are the two types of of cartridge disk-relief method?

Answer 27

-standard -high temperature/ hermetically sealed

Question 28

What are discharge indicators and their types?

Answer 28

Visual evidence of discharge -thermal indicator (red) -discharge indicator (yellow)

Question 29

What is the purpose of a thermal discharge indicator?

Answer 29

To show when an indicator has been expelled overboard due to excesive heat

Question 30

What is the purpose of a discharge indicator?

Answer 30

When the fire crew activate the extinguisher a yellow dish shows visually that it has happened

Question 31

How does the engine fire systems function?

Answer 31

-It is electrically operated after manual selection by flight crew after fire detection -regulation states it must be ‘two shot’ -a pipe with a spray nozzle at the engine

Question 32

What occurs when the fire push button is pressed?

Answer 32

-the engine driven generator is switched off -all associated bleed air valves close -low pressure fuel shut off valve closes -central warning system gets a signal and updates the flight deck display -finally the firing circuits are armed and ready to fire

Question 33

When must the second bottle be discharged?

Answer 33

If the fire is still present after 30 seconds

Question 34

What occurs when the agent push button is pressed?

Answer 34

A squib is heated exploding the cartridge rupturing the tangible disk

Question 35

What precautions are taken against HIRF on squibs?

Answer 35

-screening of sensitive cables -HIRF on filters -place in faraday cage -ensure good bonding

Question 36

How does the lavatory fire extinguisher system function?

Answer 36

-Halon 1301 -76 degrees the seal melts

Question 37

How many fire extinguishers are needed per number of seats?

Answer 37

7-30 / 1 31-60 / 2 61-200 / 3 201-300 / 4 301-400 / 5 401-500 / 6 501-600 / 7 600 + / 8

Question 38

What type of fire extinguishers are used on on aircraft and why?

Answer 38

Halogenated hydrocarbons Low toxicity, no residue, non conductive Halon 1301 Halon 1211 Class A, B, C can be used

Question 39

What is replacing halon?

Answer 39

-HCFC blend B -HFC- 227ea -HFC- 236fa

Question 40

Where is CO2 used?

Answer 40

On the ramp

Question 41

What are the advantages of CO2 and where can it be used?

Answer 41

Can be used in the engine or APU externally fluid/ electrical non reactive and non combustible It smothers as its 1.5x heavier than air

Question 42

Why are dry powder extinguishers less useful?

Answer 42

They require clean up

Question 43

What is a class A compartment?

Answer 43

-you can visually identify smoke -they are accessible in flight -there is a presence of extinguishing systems

Question 44

What is a class B compartment?

Answer 44

-there is sufficient access in flight -when accessed a hazardous quantity of smoke flames or extinguisher will enter the cabin -each compartment is equipped with a fire detector -portable extinguishers can be used

Question 45

What is a class C compartment?

Answer 45

-there is a separate smoke detector -there is a separate built in extinguisher -smoke and fumes are contained -ventilation can be controlled

Question 46

What is a class E compartment?

Answer 46

-it has a separate smoke detector -ventilation can be shut -smoke is prevented from cabin -If there is a fire emergency exits are still accessible