15.20 Flashcards
What’s a fire zone
Areas that require fire detection or extinguishing equipment and high degree of fire resistance
What is thermodynamic failure
Cooling cycle is upset that causes turbine blades to melt
What is mechanical turbine failure
Fractured or thrown blades
3 types of fire detection
Over heat detectors
Rate of temperature rise detectors
Flame detectors
What’s a spot sensor used for
Uses individual sensors to monitor a fire zone
What type of sensor is employed on transport aircraft
Continuous loop system
How does a thermal switch work
Once temperature is above the set value the switch will close and generate a fire or overheat condition
How can we test lights
Bulb is tested by pressing it in to check an auxiliary test circuit
How does a thermocouple system work
Works on the rate of temperature rise detectors
If hot junction heats quicker then reference junction signal is given
What are optical sensors referred to as
Flame detectors
How do flame detectors work and what’s the 2 types
Detect presence of specific radiation emissions from hydrocarbon flames
IR & UV (uv used on light turboprop and helicopters)
How does pneumatic thermal fire detection work
As the gas is heated pressure causes switch to close the reports alarm
How is the average function activated
Expansion of a fixed volume of helium gas inside the detector
Average temperature sensor pre set temperature range
93-371 degrees C
Discrete temperature sensing range
1100 degrees C for 5 seconds
How does a discrete temperature sensor work
Outgassing of hydrogen from the core increases presssure and activates alarm switch
What temperature sensings are reversible
Discrete and average
Manufacture names of sensing systems
Lindberg , systron donner & meggitt
What’s an advantage of dual loop
Increase the reliability of the system
Manufactures of continuous loop detector systems
Fenwal & kiddie
What material does fenwal use
Slender inconel tube
What are the parts of a kiddie system
Two wires embedded in an inconel tube filled with thermistor core material
How does kiddie system work
As temperature increases resistance to the ground decreases once it hits a certain resistance overheat indication appears in flight deck
Advantage of sensing element
Can be routed close to non-hazardous hot spots that have normal temperature above the alarm temperature without causing a false alarm
What’s the benefit to AND logic
Better reliably against false warnings
What’s a dual loop system
Two complete fire detection systems with their output signals connected so that both must signal to result in a fire warning
What test is done on a dual loop system
Pre flight integrity test
What are transport category certified aircraft required to have
Two discharges
Where is the single shot system used
Apu
Fuel burning
Heaters
Combustion equipment
What is the most common extinguishing agent
Halon 1301
What are fire bottles pressurised with
Nitrogen
When is spherical designs used
Lightweight and when space is limited
What’s a simple visual indicated gauge
Vibration-resistant helical bourdon type indicator
What’s a benefit to a combination gauge
It provides an electrical signal if pressure is lost
No need to discharge indicators
What does a red disc show
Contents has been dumped overboard due to excessive heat
What does a yellow disc show
Extinguisher has been activated by the flight crew
Where a fire switches
Centre overhead and awl or centre console in flight deck
