Engine Fire Protection Systems Flashcards
What are four types of engine fire detection systems?
Thermoswitch system, thermocouple system, thermistor-type continuous-loop system, pneumatic-type continuous-loop system.
Which type of fire detection system operates on the principle of the rate of temperature rise?
The thermocouple system.
Why must the reference junction in a thermocouple fire detection system be thermally insulated?
This is a rate-of-temperature-rise system. The reference junction must be insulated so its temperature will not rise as quickly as that of the measuring junctions if a fire should occur.
How do you check a thermocouple fire detection system for operation?
Press the test switch. This heats the test thermocouple enough for it to close the sensitive relay, which in turn closes the slave relay and activates the fire warning light and bell.
What would likely cause a false fire alarm in a thermistor-type continuous-loop system?
A kinked or pinched continuous-loop element.
If there is a break in a single-wire continuous-loop fire detector element, and the system tests bad, will it indicate the presence of a fire?
Yes, even though it tests bad, it will still indicate the presence of a fire.
How is a pneumatic-type continuous-loop fire detection system checked for operation?
When the test switch is closed, low-voltage AC flows through the tube that encloses the sensitive element. This current heats the element enough for it to release sufficient gas to activate the alarm switch.
What maintenance is allowed on a continuous-loop fire detection system?
Inspect and replace as needed the continuous-loop element, the controller, and the fire warning bell and/or light.
What happens in a jet transport airplane when the fire-pull T-handle for an engine is pulled?
The engine fuel shutoff valve is closed. The generator field relay is tripped. The compressor bleed air valve is closed. The anti-ice valve is closed. The hydraulic supply shutoff valve is closed. The hydraulic pump low-pressure warning lights are turned off.
What is used as a fire extinguishing agent in some older aircraft?
Carbon dioxide (CO2).
What fire extinguishing agent is used in the high-rate discharge bottles installed in a jet transport aircraft?
Halon 1211 or 1301.
How is a high-rate discharge bottle of fire extinguishing agent discharged?
A powder charge is ignited and it blows a cutter through a frangible disk that seals the bottle.
What precaution must be taken when checking the electrical circuit for igniting the powder charge in the valve of a high-rate discharge bottle?
The current used to check the integrity of the electric circuit must not be high enough to ignite the powder charge.
What is indicated if the red discharge indicator for a fire extinguishing system is blown out?
The system has been discharged by an overheat condition.
What is indicated if the yellow discharge indicator for a fire extinguishing system is blown out?
The system has been discharged by actuating the bottle discharge switch.
