Airframe Fire Protection Systems

Question 1

What is a Class B fire?

Answer 1

Class B fires are those caused by combustible fluids.

Question 2

What are the three elements required for a fire?

Answer 2

Fuel, oxygen, and high enough temperature.

Question 3

What is a fire zone on an aircraft?

Answer 3

A fire zone is an area or region of an aircraft designed by the manufacturer to require fire detection and/or fire extinguishing equipment and a high degree of inherent fire resistance.

Question 4

What type of fire detection system is usually used in engine compartments, APU installations, and wheel wells?

Answer 4

A continuous-loop fire detection system.

Question 5

Does a thermocouple fire detection system warn the pilot of a general overheat condition?

Answer 5

No, it operates on the rate of temperature rise, and it detects only a fire.

Question 6

Does a thermal switch fire detection warn the pilot of a general overheat condition?

Answer 6

No, it actuates only when there is a fire.

Question 7

Does a pneumatic fire detection system warn the pilot of a general overheat condition?

Answer 7

Yes, it actuates when there is a fire or a general overheat condition.

Question 8

How is a thermoswitch fire detector circuit checked?

Answer 8

Close the test switch. If the system is continuous and not shorted, the fire-warning light and bell will actuate. Failure of the warning light to illuminate shows they system is faulty.

Question 9

how is a continuous-loop fire detector circuit checked?

Answer 9

Close the test switch. Fi the system is continuous and not shorted, the fire-warning light and bell will actuate. Failure of the warning light to illuminate shows the system is faulty.

Question 10

How is the pneumatic fire detection system tested?

Answer 10

When the test switch is closed, low-voltage AC flows through the stainless steel tube in which the gas absorbing element is housed. This current heats the element which releases gas and actuates the fire warning light and bell.

Question 11

What type of detector is commonly used in baggage compartment and holds?

Answer 11

Smoke detectors.

Question 12

What type of detector is usually used in the flight deck and cabin areas?

Answer 12

CO detectors.

Question 13

What type of fire extinguishing agent is best for both cabin fires and engine fires?

Answer 13

Halon 1301.

Question 14

What types of fire extinguishing agents should not be used in aircraft cabins or flight decks?

Answer 14

CO2, dry chemicals, or specialized dry powders.

Question 15

What is a major disadvantage of “CB” fire extinguishing agent for extinguishing aircraft fires?

Answer 15

It is corrosive to aluminum and magnesium.

Question 16

Why is carbon tetrachloride not recommended as a fire extinguishing agent?

Answer 16

Carbon tetrachloride produces phosgene, a deadly gas, when it is exposed to flames.

Question 17

What is used as a fire extinguishing agent in most of the high-rate discharge systems installed in aircraft?

Answer 17

One of the halogenated hydrocarbons, such as Halon 1301, pressurized with nitrogen.

Question 18

What releases the fire extinguishing agent in a high-rate discharge bottle?

Answer 18

An electrically ignited powder charge blows a knife through a seal in the HRD bottle.

Question 19

What happens when the Fire-Pull T-handle is pulled in a jet transport aircraft?

Answer 19

The bottle discharge switch is uncovered and armed, the generator field relay is tripped, fuel is shut off to the engine, and hydraulic fluid is shut off to the pump. The engine bleed air is shut off and the hydraulic pump low-pressure lights are deactivated.

Question 20

What must be done to release the fire extinguishing agent after the Fire-pull T-handle has been pulled?

Answer 20

The bottle discharge switch must be closed.

Question 21

what type of fire extinguisher is recommended for extinguishing a brake fire?

Answer 21

A dry-powder type extinguisher.

Question 22

how can you determine the state of charge of a CO2 fire extinguisher?

Answer 22

By its weight.

Question 23

How can you determine the state of charge of a freon fire extinguisher container?

Answer 23

By the pressure shown on the built-in gauge.

Question 24

How does the ambient temperature affect the pressure shown on the pressure gauge on a freon fire extinguisher?

Answer 24

The higher temperature, the higher the pressure.

Question 25

How can you determine whether or not a built-in fire extinguishing system has been discharged?

Answer 25

By checking the blowout plugs on the outside of the aircraft near the extinguisher agent bottles.

Question 26

What is indicated if the red disc in a built-in fire extinguishing system is blown out?

Answer 26

The agent bottle has been discharged by the flight crew actuating the Bottle Discharge switch.

Question 27

What precaution must you observe when checking the electrical squib of a HRD fire extinguisher bottle for electrical continuity?

Answer 27

It takes only a small amount of current to ignite the powder charge, and the method of testing must not send this amount of current through it.

Question 28

Why is it important to use proper PPE when working on or testing fire extinguishing systems?

Answer 28

Some fire extinguishing systems operate under very high pressures, using chemicals that can be hazardous to one’s health. Proper PPE should always be used to protect the individuals working on the systems.

Question 29

What are the risks of using improper fire extinguishing agents?

Answer 29

The use of improper fire extinguishing agents can be ineffective for the fire at hand. In some cases, use of an incorrect agent in an enclosed area may make it difficult for individuals to breathe.