Fire/Smoke Detection Flashcards
Fire bottles are
Electrically operated manual selection by flight crew
Based upon automatic fire detection
Each engine has two fire extinguisher bottles available which are connected to fire zones via piping
Release the content if the cartridge is broken
What happens when you pull the fire warning handle
Fire bottle squib will be armed
- closure of fuel shut off valve
- closure of hydraulic shut off valve
- closure of engine bleed air valve
- tripping of generator breaker
- disabling the engine thrust reverser
Gas filled fire detection system error warning means
Low Pressure
Gas filled detection system fire warning means
High pressure
Gas filled fire detection system
If the gas in the pipe is heated pressure rises to warn the presence of fire
Optical Smoke Detector
Particles of smoke scatter and reflect light
Detector has a light source and a sensor
If two or more detectors sense smoke it will trigger alarm
Ionisation Smoke Detector
Small quantity of radioactive material in ionising chamber
Smoke particles absorb alpha particles
Ionisation stops so current flow stops
Lack of current flow triggers warning on flight deck
APU Fire Zone
Self contained/automatic detection will cause APU to shut down
Fire wire - Fire Detection
Operates on principal wire will change its resistance when heated
Can be operated with one loop for limited time
Each loop is independent of other and own controller
Systron Donner - Gas Filled Detector
Two loops which gas expands to push out warning circuit
Core contains helium gas 8psi
If loop breaks gas leaks and responder unit will signal fault
Bimetallic overheat sensor
Two metallic strips with low efficient of expansion
Electrical contact
Heat stretch them apart
Armed condition for fire warning in cockpit
Pulling fire warning will
Cut of generators
Cut of fuel supply low pressure spar valve
Cut of hydraulic supply
Cut of bleed air/HPSOV
Detonator arms the fire extinguisher squib
Can be reversed apart from generators is pushed back in
After arming the fire warning what is the next step
Rotate the red button which will fire the squib
When fire is detected
Red flashing fire master caution captions (will not go out until fire detection is removed)
Sound of fire warning bell
Illuminate the ENG1 FIRE
Illuminate appropriate fire handle in cockpit
Fire extinguisher system is a
2 shot system capable of sending extinguishing to either engine
Toilets have what fire smoke/fire protection
Smoke detection is ionisation type
Automatic fire extinguisher straight into the waste paper bin
Freon/BCG extinguishing agent
Fire extinguishers in engine
Operated by electrically fired cartridge (squib) rupturing a seal in the bottle head
Extinguishing directed to low pressure end of the engine compressor
X2 per engine
Halon extinguisher used
Fire Wire faults meaning
Low resistance and low capacity - loop is faulty
Indications of successful engine fire drill
The engine fire handle or button light goes out
What warnings of an engine fire system can be cancelled
The audible warning and attention getting light
Red fire captions illuminated until fire is no longer detected
Firewire works on a negative of what
Negative coefficient of resistance and a positive coefficient of capacitance
Smoke Detection requirements in flight deck
No required
Where would you find smoke detectors
Galleys, toilets and inaccessible compartments and worse case scenario area
- hydraulic bays
- cargo bays
- avionics
- electrical bays
- engines
- APU
- Cargo compartments
Continuous Loop Fire detection system
Thermal detector that monitor temp and heat and responds with signal when temp exceeds limit
Changes electrical resistance with temp - as temp goes up resistance goes down and current increases. Can be reset once fire is removed as resistance will then increase again
Dual loop system both need to be triggered to activate fire warning
Minimum loops for a 2 engine ac
2 loops minimum
One loop has 2 shots
Why do bimetallic detectors have a delay before triggering
In order to avoid false indications caused by vibrations
Key facts about halon extinguisher
Suppresses the chemical reaction of fire
Most effective fire extinguisher
Is not corrosive on aluminium
