Answers - Fire Protection System

Fill in the Blanks

1. a fixed fire protection
2. thermal switch system, thermocouple system, continuousloop detector system.
3. rate of temperature rise, slowly
4. chromel and constantan
5. thermistor, Lingberg
6. nacelle temperature
7. AND
8. Systron‐Donner, Meggitt safety systems
9. lavatories, cargo, smoke
10. flame detectors
11. reciprocating, carbon monoxide, exhaust system
12. water, ignition
13. Carbon dioxide
14. high Rate of Discharge (HRD), 1 to 2
15. liquid, gas


1. true
2. false
3. false
4. false
5. true
6. false
7. true
8. true
9. false
10. true

Knowledge Application

1. Engines and APU, Cargo and baggage compartments, Lavatories, Electronic bays, Wheel wells, Bleed air ducts.
2. Overheat detectors, Rate‐of‐temperature‐rise detectors, Flame detectors, Observation by crewmembers.
3. Rate‐of‐temperature‐rise detectors, Radiation sensing detectors, Smoke detectors, Overheat detectors, CO2 detectors, Combustible mixture detectors, Optical detectors.
4. Fenwal, Kidde, and Lingberg
5. Precise fit, eliminates chafing, and quick and easy to install.
6. Fire detection and extinguishing for engines, APUs, cargo bays, and bleed air systems.
7. Halocarbon Clean Agents, Halon, and dry powders.
8. Turbine engines, APU, Cargo compartments, lavatories
9. cartridge (squib) and frangible disc type valve
10. to rupture the frangible disk
11. This is an indication for the maintenance crew that the fire extinguishing system was activated by the flight crew.
12. The engine will stop because the fuel control shuts off, the engine will be isolated from the aircraft systems, and the fire extinguishing system will be activated.
13. The presence of a fire would be easily discovered by a crewmember while at his station; and each part of the compartment is easily accessible in flight.
14. Class B has a smoke detector or fire detection system.
15. The master warning lights come on, the fire warning aural operates, a cargo fire warning message shows, the cargo fire warning light comes on.
16. Kinks and sharp bends can cause an internal wire to short intermittently to the outer tubing and cause false alarms.
17. 550 psi

Multiple Choices

1. b
FAR 23.853(a) Passenger and Crew Compartment Interiors. For each compartment to be used by the crew or passengers, the materials must be at least flame resistant.

2. c
Carbon Monoxide(C0) detectors are used to sense the presence of deadly carbon monoxide gas and are primarily found in aircraft cabins or cockpits.

3. a
On a few aircraft, visual smoke detectors provide the only means of smoke detection. When smoke is present, the light from an internal lamp is reflected by the smoke and the light illuminates a panel within the indicator, indicating the presence of smoke.

4. a
Fire protection for the aircraft interior is usually provided by hand-held extinguishers. Four types of fire extinguishers are available for extinguishing interior fires: (1) water (2) carbon dioxide (3) dry chemical, and (4) halogenated hydrocarbons.

5. b
There are several types of portable carbon monoxide testers in use. One type has a replaceable indicator tube that contains a yellow silica gel. During operation, a sample of air is drawn through the detector tube. When the air sample contains carbon monoxide, the yellow silica gel turns to a shade of green. The intensity of the green color is proportional to the concentration of carbon monoxide in the air sample at the time and location of the tests.

6. a
Smoke detection instruments are classified by method of detection, and, in some cases, an aircraft will have different types of detectors installed in various locations.

7. c
Photoelectric smoke detectors consist of a photoelectric cell, a beacon lamp, and a light trap, all mounted on a labyrinth. Air samples are drawn through the detector unit, usually by a small circulating fan. When smoke particles are present, they refract light into the photoelectric cell. An accumulation of 10% smoke in the air causes the photoelectric cell to conduct electric current. When activated by smoke, the detector supplies a signal to a smoke detector amplifier, which activates a warning light and aural warning.

8. a
The portable carbon monoxide tester which has the yellow silica gel is returned to service after contamination by replacing the tube which contains the gel.

9. c
In a typical thermocouple system, one or more thermocouples, called active thermocouples are placed in fire zones around an engine while a separate thermocouple, called the reference thermocouple, is placed in a dead air space between two insulated blocks. Under normal operations, the temperature of the air surrounding the reference thermocouple and the active thermocouples are relatively even and no current is produced to activate a warning light. However, when a fire occurs, the air temperature around the active thermocouples rises much faster than the air temperature around the reference thermocouple. The difference in temperature produces a current in the thermocouple circuit and activates a warning light and horn. A thermocouple depends upon the rate of temperature rise and will not give a warning when an engine slowly overheats or a short circuit develops.

10. b
A carbon dioxide hand held fire extinguisher can be used on an electrical fire, provided the discharge horn is made from a nonmetallic material. A metallic horn would tend to transfer an electrical charge back to the fire extinguisher and to ground through the person holding the extinguisher.

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