15.20 Fire Protection Systems Flashcards
What is a fire zone
Area of an aircraft that requires fire detection and/or extinguishing equipment.
What else is needed in a fire zone
High degree of fire protection
What must multi engine aircraft have
Engine fire protection system
What are the two types of turbine failure
-Thermodynamic
-Mechanical
What is thermodynamic turbine failure
Turbine blades can melt due to thermodynamic air upset. This causes sudden loss of thrust
What can cause overheating and blade melting
Rapid ice formation on inlet screen or inlet guide vanes
What is mechanical turbine failure
Era Fractured or thrown blades, can puncture tail cone causing overheating or fires
Why is penetration of the turbine case very bad
Can penetrate lines carrying fluids such as fuel
What is a complete fire detection system
Has extinguishing and detecting capabilities
How are fires detected on aircraft
-Overheat detectors
-Rate of temp rise detectors
-Flame detectors
What should a fire detector system be
-No false warnings
-Rapid indication of fire and reignition
-Continuous indication for time of fire
-Resistant of heat and damage
What are the two most common engine fire detectors
-Spot detectors
-Continuous loop systems
How does a spot detector work
Uses individual sensors to monitor fire zone eg. Thermal switch, thermocouple and pneumatic
How do continuous loop systems detectors work
Provide complete fire coverage use continuous thermal sensing elements for power plant protection
Example of continuous loop detectors
Fenwal
Kidde
How do thermal switches work
Heat sensitive unit will complete a circuit if it’s too hot and make a fire light light up in the cockpit
How are thermal switches connected
In parallel
How does a thermocouple fire detector work
Detects rate of temperature rise, only warns at fast temp rate increase
What does a thermocouple use to work out rate of temp increase
Has two junctions if there is a fast temperature increase a voltage is produced meaning there is a fire
How do optical fire detectors work
Use IR or UV light and detect hydrocarbon in the air
What aircraft use infrared detectors
Light turboprop aircraft and helicopters
How do pneumatic thermal fire detection work
Element is helium filled tube which expands as it is heated. Only takes an average of an area
Two types of detection in pneumatic detection
Average (uses helium) 93-371°C
Discrete (releases hydrogen when temp is 1100°C for 5 seconds)
What is the 3 names of the manufacturers making discrete pneumatic sensing
-Lindberg
-Systron-Donner
-Meggitt
What type of detectors are kidde and fenwal
Continuous thermal sensing
How many wires does kidde have
2
How many wires does fenwal have
1
How does fenwal work
Uses a tube with effective salt in and nickel wire, when it gets hot the resistance if the salt drops drastically indicating a fire
How does the kidde system work
Uses two wires, one has ground connection one without so as they get hot a resistance changes which is detected by the fire detection control unit
Example fire zones on aircarft are
-Engine power section
-Engine accessory section
-Apu compartment
-Fuel burning heaters
-Compressor
-Combustor
What fire extinguisher agent is used and why
Halon 1301 because it’s non corrosive
How many extinguisher shots for APU
1
How many extinguisher shots per engine
2
What are fire bottles made of
Stainless steel
What is the pressurised gas inside the extinguisher bottles
Nitrogen
What shape are extinguisher bottles
Spherical or cylindrical in space limiting areas
How does a discharge valve release agent
Slug driven by explosive energy ruptures the closure disc
How is fire extinguisher pressure shown
Uses an indicator gauge
What is a two way check valve for
Used in two shot system to prevent agent in the reserve container going into the main container
Purpose of red thermal indicator
Shows thermal discharge
Purpose of yellow discharge indicator
Flight crew activated fire extinguisher
