Subject I - Engine Fire Protection Systems Flashcards
What are the main categories of engine fire protection systems?
Spot-detection, continuous loop, and flame detectors.
Name examples of spot-detection type systems.
Thermal switch and thermocouple
Name examples of continuous loop detection systems
Fenwal( one “L” one wire), Kiddie(two “Ds” two wires), and pnumatic
When using a thermocouple-type fire detector system, what happens if the engine overheats slowly?
A thermocouple depends on the rate of temp rise, and will not give any warning if the engine slowly overheats or a short circuit develops.
How many thermocouples are required for engine fire detection?
The number of thermocouples used in an engine fire detection system depends on the size of the fire zone and total circuit resistance.
Describe the operation of a Kiddie continuous loop fire detector system.
The Kiddie continuous loop system has two wires embedded in a special ceramic core within an Inconel tube. One wire acts as internal ground and the other wire is a hot lead that provides current. When the ceramic core material heats up its resistance drops, completing a circuit between the internal wires, lighting a light
Where does a thermocouple fire detector system get its electrical power to operate?
The thermocouple produces power to close a relay, and power from the aircraft electrical system flows through the relay to the warning light.
Describe a thermal switch fire detector system?
Thermal switch systems have one or more lights that are energized by the aircraft’s electrical system when a heat-sensitive thermal switch closes the circuit at a specific temperature
How are thermal switches electrically connected in the circuit?
The thermal switches are connected in parallel with each other but in series with the warning light.
A temperature rise in any section of the circuit will cause a thermal switch to close and complete the circuit to indicate a fire or overheat condition
What is the most common cause of a false fire warning in a continuous loop detector system?
The common causes of false warnings are dents, kinks, or crushed sensing elements. This damage causes the internal wire to short to the ground wire or outer tubing.
Will a continuous loop fire detector still indicate the presence of a fire if the element is broken in two?
yes
What two methods are used to discharge fire extinguishing agents?
Mechanical and electrical
What method is used to release the fire extinguishing agent in a typical turbine engine fire protection system?
One common method is to equip the fire extinguishing containers with discharge valves that are operated by electrically discharged cartridges.
The discharge plugs are seated with a breakable disk that is ruptured by the explosive cartridge and the contents of the bottle are discharged into the engine area.
What method is used to determine proper fire extinguisher container pressure?
Check the container gauge to determine if the pressure is between the prescribed minimum and the maximum limits.
What is the color marking used to identify fire extinguishing lines?
A brown tag with a row of black diamonds.
What method other than the pressure gauge Is used to indicate low agent pressure in a container?
Some aircrafts are equipped with low pressure warning light in the cockpit.
What is the purpose of the yellow and red discharge plugs(disks) in a turbine engine fire extinguishing system?
The yellow plug indicates a pilot initiated the discharge. The red plug indicates thermally activated discharge.
What are two methods commonly used to distribute the fire extinguishing agent to the engine?
A perforated tube or discharge nozzles are used to distribute the agent.
How does the fire extinguishing agent put out the fire?
It dilutes the atmosphere so that it will not support combustion.
What does “HRD” stand for?
High Rate of discharge
How is the fire extinguishing agent distributed from an HRD system?
It is delivered from open-end tubes.
How long does it take to discharge the extinguishing agent in an HRD system?
It only takes 1 to 2 seconds
Which type of fire detection system gives a more complete coverage to a fire hazard?
A continuous-loop system.
