11.8 Flashcards
Whats the three things required for a fire to start ?
Fuel
Heat
Oxygen
What should fire zones be equipped with ?
Detection and extinguishing equipment.
Whats the fire zones ?
APU and engines
Baggage
Toilet
Electronic components
Wheel wells
Bleed air ducts
What should detectors not automatically do ?
Should not Operate extinguisher
Whats the 3 common fire detection systems ?
Thermal switches
Thermo couple
Loop sensing elements - most used
Explain the thermal switch system used in an aircraft to detect fire ?
Heat sensitive switches which complete a circuit at a certain temp which elominates warning lights.
( presence of a relay allows you to test the warning system )
Explain a continuous loop system used to detect a fire ?
Two types =
Fenwal system - when an overheat condition occurs at any point along the element length, the resistance of the salt drops sharply causing a current to flow between the outer sheath and the centre conductor. Current flow is sensed by control unit which produces a signal to activate the alarms. Once fire s extinguished, fenwal system returns to standby
Kiddle system - has two wires embedded in a inconel tube filled with thermistor core material. One conductor has ground connection to the tube and the other one connects to the fire detection control unit. As the temp of core increases, electrical resistance to the ground decreases. When fire is extinguished, resistance increases again and grounds warning system.
Whats the three fire detectors ?
Thermal switch
Thermocouple
Continuous loop
Note - fenwal system has one electrode whereas a Kidde system has 2
Explain dual - loop system ?
Two complete basic fire detection system with connected outputs meaning both must signal to result in a fire warning.
( increase reliability in false fire warnings )
Explain a pneumatic continuous loop system ?
-Contained gas ( helium ) expanding due to the application of heat.
-designed so that damage to sensor tube cannot result in a false alarm.
Whats the two sensing functions for a pneumatic continuous loop system ?
=Overall average temp - activated from expansion of helium gas inside detector
=Localised discrete temp increase \that was cause by flame or hot gas - hydrogen filled core material which releases hydrogen whenever part of the tube is heated for at least 5 seconds.
What are continuous lop systems passed trough to minimise abrasion ?
Rubber grommets
( must be installed on the sensing element )
Explain smoke detection system ?
Air is continually sampled into smoke detection system, any smoke found in sample causes a change in current flow. This change in current will trigger alarm
Whats the two types of smoke detector systems ?
Photoelectric
Ionisation type
What does the cargo smoke detector system consist of ?
Light emitting diodes
How many passengers should an aircraft carry for a requirement for it to instal a lavatory smoke detector system ?
20 or more
( if smoke is detected the lavatory master call light flashes and gives warning to flight attendant station. )
Whats the 4 areas on a aircraft which a fire extinguishing system is installed ?
- engines
- APU
- baggage and cargo compartment
- lavatories
( must me manually controlled )
Whats the two types of fire extinguishers ?
Fixed and portable.
Whats the most common extinguishing agent used for fixed extinguishers ?
Halon 1301
Whats the extinguishing bottles pressurised with ?
Nitrogen
- manufactured from stainless steel
Whats the two types of cartridge disk - release method ?
- standard release type - explodes and ruptures closure disk via slug drive.
- high temp sealed units - explosive impact type cartridge which ruptures a CRES diaphragm.
Whats the two extinguishing bottle pressure indications ?
Basic - shows pressure on gauge and check visibly
Combination - shows pressure on gauge which is checked visibly but also provides electrical signal if bottle pressure is lost ?
Whats the two types of discharge indicators ?
Thermal discharge indicator - red
Discharge indicator - yellow
Whats does a thermal discharge indicator ( red ) show the pilot and engineers ?
Indicates bottle contents have been dumped over board and show that the extinguisher bottle needs replacing before next flight ?
What does the discharge indicator ( yellow ) indicate to flight crew ?
Shows engineer system was activated by crew and it needs a replacement before next fight.
After activating 1st extinguishing agent How long should the fire warning stay on for the pilot to then discharge the second agent ?
30 seconds
( this means fire still exists )
What does pushing the it red fire button in the overhead panel do ?
Isolates engines from plane and arms the fire extinguishing system, then press a separate button to discharge agent into fire zone.
When should a APU automatically shut down ?
- fire
- oil pressure failure
- over speed
- over heat
Where is the discharge cartridge ( squib ) service life located ?
Stamped on front.
( 5 - 10 years )
When electrical connectors are fitted to the extinguisher bottle, what must be installed along with that ?
RADHAZ filter.
Shall the extinguisher bottle be installed assembled or disassembled?
Disassembled
What must you check when installing fire extinguishing pipes or tubing ?
Checked for freedom from obstruction by blowing through with clean, dry compressed air.
What must be checked on the spray rings when installing them to aircraft ?
Free from corrosion, cracks, dents or other deformation.
He quick should the detection system in the baggage compartment provide an indication to the fight crew of a fire starting ?
Within 60 seconds after the start of the fire.
Whats the two types of cargo fire extinguisher bottles equipped in compartment and there function ?
Dump system ( first ) - releases extinguishing agent when discharge switch is activated.
Metered system ( secondary ) - bottles which discharge at slow controlled rate to keep fire extinguished ( for 180 mins ) and minimise risk of re light
Whats placed on the side of the waste compartment to indicate there was a fire ?
Temp indicator.
How many seats should it range from to have a certain number of extinguishers ?
7 - 30 = 1
31 - 60 = 2
61 - 200 = 3
201 - 300 = 4
301 - 400 = 5
401 - 500 = 6
501 - 600 = 7
601 or more = 8
Whats the two types of halons extinguisher types ?
Halon 1301
Halon 1211
What class fires does halon extinguisher extinguish ?
ABC
( don’t use on class D )
What fire extinguisher is used on the ramp incase of an engine or APU external fire ?
C02
What class fire is c02 used on ?
Class B
What class fires can dry powder be used on ?
ABC
( limited due to heavy clean up after )
What class fires can water be used on ?
Class A
What extinguisher isn’t suitable for use n the cabin ?
Carbon dioxide
Dry chemical
Special dry powder used for ground ops
Whats the 3 things that determine the class of a fire compartment ?
- if the area is accessible
- presence of fire/smoke detector
- presence of extinguishing system.
