Powerplant Systems & Components: Engine Fire Protection 🔊 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, Kidde, and pneumatic
When using thermocouple type fire detector systems, what happens if the engine overheats slowly?
Thermocouples depend on the rate of temperature rise and will not give an indication if the engine overheats slowly or a short circuit develops
How many thermocouples are required for engine fire detection?
It depends on the size of the fire zone and the total circuit resistance
Describe the operation of the Kidde continuous loop fire detection system.
It has two wires imbedded in a ceramic core within an Inconel tube. One acts as ground and one as a hot lead that provides a current. When the ceramic core material heats up its resistance drops, completing the circuit between the wires and 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 detection system.
They have one or more lights that are energized by the aircraft electrical system when a heat sensitive thermal switch closes the circuit at a specific temperature.
How are thermal switches electrically connected in the circuit?
Thermal switches are connected in parallel with each other and in series with the warning light. 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?
Most common causes of false warnings are dents, kinks, or crushed sensing elements. The damage causes the internal wire to short to the ground or outer tubing.
Will continuous loop fire detectors 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?
Discharge valves that operate by electrically discharged cartridges. Discharge plug is seated with a breakable disk that is ruptured by the explosive cartridge (squib).
What method is used to determine proper fire extinguisher container pressure?
Check the container gauge to ensure pressure is withing prescribes minimum and maximum limits.
What is the color marking used to identify fire extinguishing lines?
Brown tag with a row of black diamonds
