Questions and Answers - Aircraft Fire Protection System

Study Aid Questions

Fill in the Blanks

1. Because fire is one of the most dangerous threats to an aircraft, the potential fire zones of modern multi‐engine aircraft are protected by _______________________________ system.

2. 3 detector systems in common use are the ____________________, _______________________, and _______________________________.

3. A thermocouple depends on the ________________________________ and will not give a warning when an engine ________________________ overheats or a short circuit develops.

4. The thermocouple is constructed of two dissimilar metals such as__________________________ and ___________________________.

5. Two widely used types of continuous‐loop systems are ___________________________ type detectors such as the Kidde and the Fenwal systems, and the pneumatic pressure detector such as the ________________________ system.

6. The Kidde continuous‐loop system can supply _______________________________ data to the airplane condition monitoring function of the Aircraft In‐flight Monitoring System.

7. Dual loop systems use a _________________ logic to increase system reliability.

8. Lindberg systems are also know as ___________________________________________ and _____________________________________________.

9. A smoke detection system monitors the____________________________, _______________________ , and baggage compartments for the presence of ________________________, which is indicative of fire condition.

10. Optical sensors often referred to as ____________________________.

11. Carbon monoxide detectors are installed in the cockpit of aircraft powered by __________________________ engines to detect for _____________________________ gas which can enter the cockpit through __________________________ malfunctions.

12. Class A type fires are best controlled with __________________________ by cooling the material below its __________________________ temperature and soaking the material to prevent re‐ignition.

13. _________________________ is not recommended for hand‐held extinguishers for internal aircraft use.

14. ___________________________________ systems use open‐end tubes to deliver a quantity of extinguishing agent in _____________________ seconds.

15. Fire extinguisher containers (HRD bottles) store a ________________________ halogenated extinguishing agent and pressurized ____________________ and are normally manufactured from stainless steel.


1. A fire protection system on most aircraft consists of a fire detection and a fire extinguishing system. TRUE/FALSE

2. Smoke detectors are not used in cargo and baggage compartments. TRUE/FALSE

3 Class D fires are fires involving energized electrical equipment where the use of an extinguishing media that is electrically nonconductive is important. TRUE/FALSE

4. Thermal switches are pressure‐sensitive units that complete electrical circuits at a certain temperature. TRUE/FALSE

5. Transport aircraft almost exclusively use continuous thermal sensing elements for power plant and wheel well protection. TRUE/FALSE

6. Halocarbon clean agents or water are used on a Class D fire. TRUE/FALSE

7. The Fenwal system uses a slender Inconel tube packed with thermally sensitive eutectic salt and a nickel wire center conductor. TRUE/FALSE

8. When the fire or overheat condition is gone, the resistance of the core material in the Kidde system will increase to the reset point and the flight deck indications go away. TRUE/FALSE

9. Pneumatic continuous loop systems are used for engine fire detection of reciprocating type aircraft and have the same function as the Kidde system; however they work on a different principle. TRUE/FALSE

10. The Lindberg fire/overheat detector's sensor tube also contains a hydrogen filled core material. TRUE/FALSE


1. Name the classes of fires that are likely to occur onboard aircraft

a. Class 1, 2, 3, and 4
b. Class I, II, III, and IV
c. Class A, B, C, and D
d. Class red, blue, green, and yellow

2. Regarding the Statements below:

#1 The Kidde system uses a slender Inconel tube packed with thermally sensitive eutectic salt and a nickel wire center conductor.

#2 In the Lindberg continuous‐loop system, two wires are imbedded in an inconel tube filled with a thermistor core material.

a. Statement 1 and 2 are true
b. Statement 1 and 2 are false
c. Statement 1 is true and statement 2 is false
d. Statement 1 is false and statement 2 is true

3. If the temperature of the Kidde continuous loop core ______ the electrical resistance to ground ______

a. increases, decreases
b. decreases, increases
c. Increases, increases
d. decreases, decreases

4. Single point pneumatic detectors that are used in some turboprop aircraft are based on the principles of ___________ laws.

a. Thermal
b. Gas
c. Newton’s
d. Hydraulic

5. Lindberg fire detection systems use a loop system that is filled with a _______ and use a ________ to actuate the control circuitry.

a. Thermistor material, pressure diaphragm
b. Thermistor material, thermocouple
c. Gas, thermocouple
d. Gas, pressure diaphragm

6. The Lindberg continuous fire detection uses __________________ gas.

a. Helium
b. Argon
c. Oxygen
d. Nitrogen

7. What type of fire extinguishing agent is an ozone depleting and global warming chemical and its production has been banned by international agreement?

a. Nitrogen
b. Helium
c. CO2
d. Halon

8. What type of fire extinguishing agent is used to fight Class A, B, or C fires?

a. CO2
b. Halocarbon clean agents
c. Dry powder
d. Answer 2 and 3 are correct

9. The most common extinguishing agent still used today is?

a. CO2
b. Halon 1201
c. Halon 1301
d. dry powder

10. The cartridge service life recommended by the manufacturer is usually in terms of _________.

a. days
b. years
c. months
d. flight cycles

Knowledge Application Questions

1. Name 5 typical zones on aircraft that have a fixed fire detection and/or fire extinguisher system?

2. What types of systems are used to detect fires in reciprocating engine and small turboprop aircraft?

3. What types of systems are used to detect fire in turbine engine fire protection systems?

4. Name 3 types of continuous loop fire detection systems.

5. What are the advantages of using Support tube mounted sensing elements?

6. What type of fire detection and extinguishing systems are controlled by advanced detection system circuitry?

7. What type of extinguishing agents are used for a class A, B, and C fire?

8. Transport aircraft have fixed fire extinguishing systems installed in:

9. What is installed in the outlet of the discharge valve?

10. What is the function of the cartridge (squib) that is installed in the discharge valve?

11. What is the purpose of the Yellow disk discharge indicator?

12. What will happen when the fire switch is activated?

13. What is a Class A cargo or baggage compartment?

14. What is the difference between a Class A and a Class B cargo and baggage compartment?

15. What indications will occur in the cockpit if there is smoke in a cargo compartment?

16. What could be the results of kinks and sharp bends in the sensing element?

17. Using the pressure chart below. What is the minimum pressure when the temperature is 70°F?

Aircraft fire detection

Multiple Choices Questions

1. A squib, as used in a fire protection system is a:

a. temperature sensing device
b. device for causing the fire extinguishing agent to be released
c. probe used for installing frangible disks in extinguisher bottles

2. When used in fire detection systems having a single indicator light, thermal switches are wired in:

a. parallel with each other and in series with the light
b. series with each other and the light
c. series with each other and parallel with the light

3. Regarding the following statements in reference to aircraft fire extinguishing systems:

(1) during removal or installation, the terminals of discharge cartridges should be grounded or shorted.

(2) before connecting cartridge terminals to the electrical system, the system should be checked with a voltmeter to see that no voltage exists at the terminal connections.

a. only number 2 is true
b. both number 1 and number 2 are true
c. neither number 1 nor number 2 are true

4. Referring to the chart below , determine the temperature range for a fire extinguishing agent storage container with a pressure of 330 PSIG. (Consider 330 PSIG for both minimum and maximum pressure.)

a. 47 to 73 °F
b. 47 to 71 °F
c. 45 to 73 °F

Aircraft fire detection

5. What method is used to detect the thermal discharge of a built‐in fire extinguisher system?

a. A discoloring of the yellow plastic disk in the thermal discharge line
b. A rupture of the red plastic disk in the thermal discharge line
c. The thermal plug missing from the side of the bottle

6. The thermal switches of a bimetallic thermal switch type fire detection system are heat sensitive units that complete circuits at a certain temperature. They are connected in__________ .

a. parallel with each other, and in parallel with the indicator lights
b. parallel with each other, but in series with the indicator lights
c. series with each other, but in parallel with the indicator lights

7. Referring to the chart above, determine what pressure is acceptable for a fire extinguisher when the surrounding area temperature is 33 °F. (Rounded to the nearest whole number.)

a. 215 to 302 PSIG
b. 214 to 301 PSIG
c. 215 to 301 PSIG

8. On a periodic check of fire extinguisher containers, the pressure was not between minimum and maximum limits. What procedure should be followed?

a. release pressure if above limits
b. replace the extinguisher container
c. increase pressure if below limits

9. In some fire extinguishing systems, evidence that the system has been intentionally discharged is indicated by the absence of a:

a. red disk on the side of the fuselage
b. green disk on the side of the fuselage
c. yellow disk on the side of the fuselage

10. The thermocouple fire warning system is activated by a:

a. certain temperature
b. core resistance drop
c. rate of temperature rise

11. Maintenance of fire detection systems includes the :

a. repair of damaged sensing elements
b. removal of excessive loop or element material
c. replacement of damaged sensing elements

12. A carbon dioxide (CO2) hand held fire extinguisher may be used on an electrical fire if the:

a. horn is nonmetallic
b. handle is insulated
c. horn is nonmagnetic

13. Which fire extinguishing agent is considered to be the least toxic?

a. carbon dioxide
b. bromotrifluoromethane (Halon 1301)
c. bromochloromethane (Halon 1011)

14. Which fire detection system measures temperature rise compared to a reference temperature?

a. fenwal continuous loop
b. Lindberg continuous element
c. thermocouple

15. In what area of an aircraft would you find a carbon monoxide detector?

a. surface combustion heater compartment
b. cockpit and/or cabin
c. engine and/or nacelle

16. What occurs when a visual smoke detector is activated?

a. A warning bell within the indicator alarms automatically
b. A lamp within the indicator illuminates automatically
c. The test lamp illuminates and an alarm is provided automatically

17. The types of fire extinguishing agents for aircraft interior fires are

a. water, carbon dioxide, dry chemical, and halogenated hydrocarbons
b. water, dry chemical, methyl bromide, and chlorobromomethane
c. water, carbon tetrachloride, carbon dioxide, and dry chemical

18. When air samples contain carbon monoxide, portable carbon monoxide detectors containing yellow silica gel will turn which color?

a. blue
b. green
c. red

19. Smoke detection instruments are classified by their method of:

a. construction
b. maintenance
c. detection

20. Smoke in the cargo and/or baggage compartment of an aircraft is commonly detected by which instrument?

a. chemical reactor
b. photoelectric cell
c. sniffer

21. A contaminated carbon monoxide portable test unit would be returned to service by :

a. heating the indicating element to 300° F to reactivate the chemical
b. installing a new indicating element
c. evacuating the indicating element with CO2

22. A thermocouple in a fire detection system causes the warning system to operate because:

a. it generates a small current when heated
b. heat decreases its electrical resistance
c. it expands when heated and forms a ground for the warning system

23. The proper fire extinguishing agent to use on an aircraft brake fire is:

a. water
b. carbon dioxide
c. dry powder chemical

24. Why does the Fenwal fire detection system use spot detectors wired parallel between two separate circuits?

a. a control unit is used to isolate the bad system in case of malfunction
b. this installation is equal to two systems: a main system and a reserve system
c. a short may exist in either circuit without causing a false fire warning

25. A fire extinguisher container can be checked to determine its charge by :

a. attaching a remote pressure gauge
b. weighing the container and its contents
c. a hydrostatic test

Fire Detection/Overheat Systems
Smoke, Flame, and Carbon Monoxide Detection Systems
Extinguishing Agents and Portable Fire Extinguishers
Installed Fire Extinguishing Systems
Cargo Fire Detection
Lavatory Smoke Detectors
Fire Detection System Maintenance and Troubleshooting
Fire Extinguisher System Maintenance Fire Prevention
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