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Where would a CO detector be found in an aircraft?
Cabin/cockpit/wherever the humans are
How can you check the charge of a fire extinguisher container if it doesn’t have a gauge?
By weighing the container and its contents.
This system measures temperature rise compared to a reference temperature.
Thermocouple
(rate of rise)
What 2 items retain the nitrogen charge and fire extinguishing agent in a high rate of discharge (HRD) container?
Frangible disk and fusible disk.
Horn must be non metallic.
Define: HRD.
High-rate-of-discharge
Alarm that allows smoke to enter the chamber, reflecting light onto the light sensor. Typically found in non-passenger areas.
Photoelectric smoke alarm
What are some things you would look for when inspecting a fire detection system?
Dents, kinks, or crushed sensor sections, cracks, breaks, abrasion, soft spots, loose clamps, unsupported sections.
Which type of system is housed in an inconel tube, like a Fenwal system, but with dual conductors embedded in thermistor material.
Kidde
Extinguishing agent that should never be applied to an electrical or flammable-liquid fire.
Water
What class of fire is comprised of combustible materials such as wood or paper?
Class A
What is inside a HRD bottle?
Nitrogen and Halon.
What color does silica CO detector turn when CO is present?
Green.
What is another name for squib?
Cartridge.
Why are smoke detectors necessary in cargo areas, instead of just fire detectors?
Because often items in cargo will give off smoke before bursting into flames, so smoke detection helps detect the condition earlier.
What does a continuous loop detector detect?
Overheat.
These system types are located in high maintenance areas and are subject to damage.
Continuous loop systems
This smoke alarm type has a small amount of radioactive material between two electrically charged plates.
Ionization-type
(When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.)
What are some ways you can check the HRD bottle pressure? Once you check it, how do you know that the charge is correct? (Describe procedure, what do you need?)
HRD bottles are checked by a built in pressure gauge or pressure switch or by bottle weight
A chart in the manual that gives the pressure limit for the existing temperature
What type of sensors do temp switch systems use?
Bimetallic.
Which is the least toxic halon?
Bromotrifluoromethane (Halon 1301).
Class of fire involving energized electrical equipment.
Class C
What is a simple type of carbon monoxide detector?
Silica crystals that change color when carbon monoxide is present.
What is the significance of the color brown with regards to fire detection in aircraft?
It is the color code for fire extinguisher lines.
What precaution do you take when installing the squib cartridge?
Before installing, check the system with a voltmeter to ensure that no voltage exists.
How does a pressure detection system work?
It only has a switch instead of needing a controller. It has an Integrity switch that opens because pressure has dropped, which indicates a leak. The gasses in the tube of a pressure system are helium and hydrogen.
What type of detector is never used in an engine nacelle? Why not?
Smoke detector. Because engines sometimes have smoke from residual oil, and a smoke detector would give a false positive of a fire.
What are the two brands of continuous loop fire detection systems?
Fenwal and Kidde.
How do the following extinguish fire?
A water spray extinguisher
a CO2 extinguisher
dry powder
halon
A water spray extinguisher puts out a fire by removing heat,
a CO2 extinguisher puts out a fire by excluding oxygen
dry powder puts out a fire by covering fuel
and halon puts out a fire by disrupting reaction
If a detector has only a visible indicator light, what is it called?
A visual smoke detector.
Besides resistance between conductor and case, what other electrical property can you check on a Fenwal style detector?
End to end continuity of the center conductor.
The _____ system is wired between two parallel circuits so that a short can exist in either circuit without causing a false fire warning.
Fenwal
A longtime staple of the industry, this agent is being phased out because it is environmentally hazardous.
Halons
(Halogenated hydrocarbons)
Oil, grease, paints, jet fuel. All of these are fuel for what class of fire?
Class B
What substance binds to hemoglobin more than oxygen?
Carbon monoxide.
When this color of disk is missing, it indicates that the fire-extinguishing system was unintentionally discharged/that the contents have spilled out and overboard due to excessive heat?
Red
What precaution do you take when removing a squib cartridge?
Ground or short the terminals of the cartridge during removal or installation.
Current flows in a fire warning thermocouple circuit because of the voltage produced by the difference in the ______________ between the junctions.
Temperature.
Powerplant compartments are CLASSified into zones based on the amount of _____ through them.
Airflow
Class A, B, C, D, and X. See pg. 17-8.
The two conductor continuous loop fire detector ______________ (does or does not) detect a general overheat condition as well as a local hot spot.
Does
WHAT EVENTS TAKE PLACE WHEN THE FIRE HANDLE OR BUTTON IS PUSHED, pulled or released?
THE FUEL IS CLOSED OFF, HYDRAULICS IS OFF, ELECTRICAL GENERATOR IS DEACTIVATED AND THE ENGINE IS ISOLATED FROM THE AIRCRAFT. THE FIRE BOTTLE IS ARMED { NOT DISCHARGED }
Name at least 4 requirements for a fire detection system?
1. System must not give false warnings.
2. Must give rapid indication of a fire
3. Be able to indicate that the flames have been extinguished.
4. must be able to sound a warning
5. Must be able to continue indicating if there is a fire.
6. Be able to be tested from the cockpit.
7. Detectors can not be in a position to be damaged by engine fluids.
8. Must be lightweight
9. Circuitry must operate directly from the electrical system.
If you're checking out a Fenwal detector between the center conductor and the outer case, what are you looking for when the system is cold?
You are looking for very high impedance (will also accept resistance) between the conductor and the case.
Also called spot detectors, _____ are heat-sensitive units that complete electrical circuits at a certain temperature.
Thermal switches
What do dump bottles do and what do metered bottles do? Where are they located?
Dispense fire suppressant immediately, discharge slowly, after a timed delay. Cargo.
Fire in flammable metals, usually involving magnesium in the shop or aircraft wheels and brakes.
Class D
After correcting for ambient temperature, if an extinguisher container is not between the minimum and maximum limits, the container must be _____.
When this color of disk is missing, it indicates that the fire-extinguishing system was intentionally discharged.
Yellow
What does the squib do?
It explodes in response to an electrical charge, and drives a cutter through the frangible disk on the HRD bottle.
What's the difference between fire detection and overheat detection?
Fire - Sharp rise in temperature over a small area; Overheat - A smaller rise in temperature over a larger area
Name the fire zones on an aircraft.
1. engine area
2. APU compartment
3.cargo/baggage area,
4. Lavs
5. EE bays
6. Bleed air ducts
What can a continuous loop system do that a point system like a thermoswitch or a thermocouple not do?
Detects fires between points.