Aircraft Systems Part 4(Fire Detection) Flashcards
Which class of fire:
Fires in ordinary types of materials such as wood, cloth, paper, upholstery materials, etc
Class A
Which class of fire:
Fires arising from flammable petroleum fluids, greases, solvents or paints
Class B
Which class of fire:
Fires arising from electrically energised equipment
Class C
Which class of fire:
Fires during which metal, such as magnesium, burns. such fires are normally associated with brakes and wheels.
Class D
The two classes of fire fighting equipment
- Portable fire extinguishers
2. fixed equipment to deal with engine fires
Which type of fire detection device:
When subjected to high temperatures, the different expansion rate of two metals cause distortion which closes an electrical circuit and activates a visual and audible alarm in the cockpit. A safety measure, in the form of a time delay, is incorporated in this type of system to ensure that the alarm is not triggered due to vibrations
Bi-metallic switch
Which type of fire detection device:
When subjected to high temperatures the dissimilar metals produce weak current which trips a sensitive relay. The electrical circuit is thus completed and a warning light and audible alarm is activated in the cockpit.
Thermo-couple type switch
Which type of fire detection device:
This the most modern system in use due to its simplicity and is often used in confined spaces, such as the engine compartment. A continuous wire, mounted inside a stainless steel tube, (earthed to the aeroplane), protected by temperature sensitive and semi-conductive insulation known as “thermister”, is routed through the various compartments. The insulating material changes with temperature; an increase in temperature causes a decrease in resistance. In other words it has the property of becoming a conductor of electrical energy instead of an insulator once a certain temperature is reached. Completing the circuit which activates the relevant warnings.
Fire wire or live wire detection system
Which type of fire detection device:
This system is also used in engine fire detection and, operates on the principle that if a gas is heated it will expand and, if contained within a sealed chamber, will cause an increase in pressure which can be used to operate a pressure switch.
Gas filled detectors
Which type of fire extinguishing agent:
Stored in grey containers and used in portable hand held extinguishers, can be used on class A fires only. Should never be used on electrical fires.
water or /water/glycol
Which type of inert cold gas fire extinguishing agent:
Stored under pressure so that it becomes a liquid this substance is used on flammable fuel and electrical fires. It is non-toxic, non-corrosive, safe to handle and is relatively inexpensive to produce.
Carbon Dioxide (CO2)
Which type of inert cold gas fire extinguishing agent:
It is very low in toxicity. Principle of extinguishers occurs by oxygen dilution which causes smothering of the flame. The main disadvantage is that it must be stores as a liquid at a temperature of -320F
Nitrogen (N3)
Which type of hydrocarbon compound fire extinguishing agent:
This substance, stored in blue containers, is confined to fixed power plant systems because it is highly toxic. For this reason it is combined with a coloured smoke as a warning
Methyl Bromide
Which type hydrocarbon compound fire extinguishing agent:
This is very an effective non toxic agent and is used in fixed systems, APU’s and cargo compartments. Stored in grey containers it is also known as Halon 1301
bromotriflouromethane (BTM)
All hydrocarbon compound agents are marketed under the name -
FREON
