11.8 Flashcards
What type of fire detectors do most modern ac use
Continuous loop
What are thermal switch systems
Heat sensitive units that complete electrical circuits at a certain temp
When temp gets to certain value it shuts thermal switch and completes light circuiy
How are the thermal switches connected
In parallel to each other
How does a thermocouple system work
Works on the rate of the change in temp and doesn’t give a indication when it slowly overheats or when a short circuit occurs
Two dissimilar metals (chrome and constantan)
What’s the usual circuit resistance of a thermocouple detector
5 ohms
What’s the usual circuit resistance of a thermocouple detector
5 ohms
What’s the usual circuit resistance of a thermocouple detector
5 ohms
What type of fire detector covers the most coverage of a fire hazard area
Continuous loop
What’s the fenwal fire detection system made up of
How’s it work
Inconel tube which contains thermally sensitive eutectic salt with a nickel wire conductor
The control unit provides a constant small voltage to the sensing elements and when an overheat condition occurs the resistance of the eutetic salt drops and causes a current flow between the outer sheath and central conductor and this current is sensed by the control unit which will set off alarms
What’s the difference between fenwal and Kidde systems
Both in inconel tubes but fenwal only has one conductive wire
Where do the two conductors in the Kidde system go
One goes to ground connection
Other to the fire detection control unit
What’s a positive of a dual loop system
Both loops must signal to get a fire warning which provides more reliability from false alarms
What happens is one of the dual loop sensors is faulty
Is deactivated using a flight deck selector switch and allows signals to come from just one of the sensors
What principle does a pneumatic continuous loop system work on
On gas expanding when subjected to heat
How are pneumatic continuous loops protected from false warnings
When there’s damage the unit gibes a “no test” indicator
What two sensing functions does the pneumatic detector have
Overall temp threshold
And a localised discrete temp caused by flame or hot gas’s
At what temp is the hydrogen gas released in the discrete temp sensor
When a small section if the tube is heated to pre set discreet temp within the range of 1100 c
At what temp is the hydrogen gas released in the discrete temp sensor
When a small section if the tube is heated to pre set discreet temp within the range of 1100 c
What type of configuration are these alarms; Lingberg System, Systron-Donner and Meggitt Safety Systems
Dual loop
Reliability
How are the Lingberg System, Systron-Donner and Meggitt Safety Systems made up
Steel tube filled with helium and have a length of titanium through the centre
If there’s a failure to get an alarm on the fire detection system what can be the cause for this
Defective test switch or control unit
How’s ionisation typensmoke detector work
Small piece of radioactive material and an electrode opposite each other
This radioactive material then causes ionisation of oxygen and nitrogen in the air ans then the current can ass across the electrodes via the ionised gas and when smoke comes in it affects the current and if the current goes below the a set value it will set off the alarm
What capacity ac require a smoke detector in the lavatories
More than 20 seats
What electricity powers the lavatories smoke detector
28 Vdc
What’s the most common extinguishing agent today
Halon 1301
Due to it not being very toxic and goof fire fighting
What date did ICAO state that all new ac applying for type certificates should now have replaced halon 1301
28 November 2024
What are fire extinguishing bottles pressurised with
Nitrogen
What are fire extinguisher bottles made off
Steel and titanium
What’s in place to prevent the bottle from exceeding the bottle test pressure when exposured to excessive temps
A temp/pressure sensitive safety relief diaphragm
What are the two types of extinguishint discharge valve
Standard release- uses a slug driven by explosive energy to rupture a segmented closure disk
Use direct explosive impact type cartridge that that applies fragmentation impact to rupture a pre stressedCRES diaphragm
What type of pressure indicator is used on fire bottles
Why is it used
Helical bourbon type
Vibration system
Why’s a two way check valve used on twin engine aircraft extinguishent bottles
To prevent back flow of the agent backing up into the previously emptied container
What does the red fire bottle discharge indicator mean
Yellow discharge indicator mean?
Red- when ur discharges due to overheating
Yellow- activated by flight crew
How many shots are engine extinguisher systems
2
What must be done to the engine before the extinguishing agent is discharged
Engine must be shut down and isolated from other supplies
What colour is the discharge light that shows the fire bottles empty
Amber
If the engine fire warning is still present after what period of time does the second bottle get discharged
30 seconds
What’s done to prevent the installation of a fire bottle that’s not fill
Weight checks in the bottle and the weight is compared with the weight on the bottle identification plate
What’s the usual cartridge/squid service life reccomended by the manufacturer
Usually 5 with a max life of 10
What things can be done in order to minimise risk of HIRF to fire bottle cartridges ( squibs)
Screening of cables sensitive to radio frequency induction
HIRF or RADHAZ filters, especially with explosive cartridges
Placing sensitive equipment within a Faraday Cage
Ensuring bonding of components is within specified parameters
How is the piping and tubing on fire bottles checked for freedom of obstruction
By blowing clean dry compressed nitrogen
What are All commercial aircraft required to have the regarding the capabilities for each cargo or baggage compartment
The detection system must provide a visual indication to the flight crew within 60 seconds after the start of a fire.
be capable of detecting a fire at a temp below which the structural integrity of the aircraft is substantially decreased.
There must be a provision for the flight crew to check, in flight, the functioning of each fire detector circuit.
What’s the difference between the two cargo extinguisher systems
Dump-releases the extinguisher agent when the cargo fire discharge switch is activated
Metered- releases the extinguisher agent slowly to get the correct concentrations of extinguisher to keep it extinguished for 180 mins
When are the master warning mights and aural fire warnings prevented from operating
Take off
How many nozzles does the fire extinguisher bottle have
2
AT what temp does lavatory fire extinguishers go off
76 c
What will happen when the engine fire bottle is tested
These tests will cause all of the Visual Push Button Annunciators (PBAs), Centralised Warning Panel (CWP) annunciators or messages to be displayed and aural bell and voice message warnings to initiate
What do aviation regulations state about fire extinguishers for flight crew
There must be one accessible from there seats
What capacity ac require a fire extinguisher, 2, 3, 4 etc
1= 7-30
2= 31-60
3= 61-200
4=201-300
What class fires can be controlled with halons
A, B, C
What’s the difference between halon 1301 ans 1211
1301- is mostly a gas so used in tight spaces and behind obstacles
1211- liquid so used in hand held extinguishers
What type of fires are water good for extinguishing
A
What fires are co2 extinguishers good for
B
C
What fires are dry chemicals used for
A
B
C
What fires are halon extinguishers good for
A
B
C
What type of fires are halocarbon clean agents used on
A
B
C
What type of fires do SPECIALISED dry powder extinguishers do
D
What types of fire extinguisher are UNSUITABLE for cabin fires
Carbon dioxide (CO2)
Dry chemicals
Specialised dry powder, suitable for use in ground operations
What’s a class a compartment
They provide for visual detection of smoke.
They are accessible in flight.
There is a fire extinguisher available.
What’s a class b compartment
Sufficient access is in flight to enable a crewmember to effectively reach all parts of the compartment with a portable fire extinguisher.
When the access provisions are being used, no hazardous quantity of smoke, flames, or extinguishing agent will enter any compartment occupied by the flight crew or passengers.
Each compartment shall be equipped with a separate system of an approved type of smoke or fire detector to give a warning at the pilot’s station.
Hand fire extinguishers shall be readily available for use in all compartments of this category.
What’s a class c compartment
There is a separate smoke or fire detector system to give warning to the flight crew.
There is an approved built-in fire extinguishing system controlled by the flight crew.
A means is provided to exclude hazardous quantities of smoke, flames, or other noxious gases from entering any compartment occupied by the flight crew or passengers.
Ventilation and draughts are controlled within each compartment so that the extinguishing agent used can control any fire likely to occur in the compartment.
What’s a class e compartment
Equipped with a separate system of an approved type of smoke or fire detector.
Means provided to shut off the ventilating airflow to or within the compartment. Controls for such means shall be accessible to the flight crew from within the flight deck.
Means provided to exclude hazardous quantities of smoke, flames, or noxious gases from entering the flight deck.
Required flight crew emergency exits accessible under all cargo loading conditions.
