15.20 Fire Protection Flashcards
What are the requirements for a fire zone?
They require fire detection and/or extinguishing equipment and a high degree of fire resistance
What are the two major types of turbine failure?
Thermodynamic
Mechanical
What are most thermodynamic faults caused by?
Ice, excess air bleed or leakage, faulty controls causing a compressor stall, or excessive fuel
How can ice cause thermodynamic faults?
Rapid buildup of ice on inlet screens or IGV’s can result in severe overheating causing turbine blade meltdown
What is a mechanical turbine failure?
Fractured/thrown blades can penetrate skins, tanks, lines etc - resulting in fires
A high flow of fuel through an improperly adjusted fuel nozzle
What are the two types of fire detection systems?
Spot detector system uses individual sensors to monitor a fire zone
Continuous loop detector system uses several loop type sensors
What are the examples of spot detector systems?
Thermal switch
Thermocouple
Optical based
Pneumatic based
What is a thermal switch?
Multiple heat sensitive switches that close at set temperatures. They are connected in parallel with each other but in series with indicator lights.
* no set number of switches, determined by aircraft type and manufacturer
What does the thermocouple depend on?
Rate of temperature increase
What is the thermocouple divided into?
Detector circuit
Alarm circuit
Test circuit
What must the amps be to generate a warning by closing the relay for a thermocouple?
0.004 A+
What is an optical system?
Flame detectors which detect presence of specific radiation emissions from hydrocarbon flames?
* infrared sensor used primarily on light turboprop and helicopter engine engines
What two fire protection system types are reversible? (Switch off alarm when cooled)
Pneumatic detection
Discrete sensing
What is true about a dual loop system?
Both elements must sense a fire to trigger an alarm
What is the advantage of a continuous loop system?
Permits more complete coverage and superior detection performance
What is true about the dual loop design? (4)
-Use AND logic both loops must detect a fire
-Switches to single loop if one loop fails
-Automatic self interrogation eliminates full indication and assures fire detection without at least one of the loop systems
-When one loop senses of fire, it’s interrogates the other loop to test for fire condition
What are the engine fire zones? (Six).
1- engine power section
2- engine accessories section
3- APU compartment
4- combustion equipment
5- compressor and accessory sections
6- combusted turbine and tailpipe sections that contain lines, fluids and gases
What is the extinguishing agent used in extinguishing systems? And why?
Halon 1301
It depletes ozone layer and does not support combustion
* non-corrosive low toxicity does not require cleanup after discharge
What does HRD stand for?
High rate discharge
What happens if overheat is detected?
Master caution lights
Caution aural
Engine OUHT displayed
What happens if a fire is detected?
Master warning lights
Fire warning aural
Engine fire warning message and light
Fuel control switch fire warning light
