15.20 FIRE PROTECTION ZONES👌🏼 Flashcards
2 major types of turbine failure
- thermodynamic
- mechanical
What must multi engine turbine aircraft have as a requirement
Engine fire protection system
Do APU require fire protection system
Yes
What occurs when the cooling cycle is upset
- turbine blades can melt which causes a sudden thrust loss
Explain mechanical turbine failure
-fractured or thrown blades can puncture tail cone causing overheating conditions
- can lead to fire
How are fires detected
- overheat detectors
- rate of temperature rise detectors
- flame detectors
2 most common fire detection systems are
- spot detectors
- continuous loop system
Explain a spot detector system
- individual sensors to monitor a fire zone
- e.g. thermal switch system
Explain a continuous loop system
- typically installed on transport-type aircraft
- provide more complete fire detection coverage by using several loop type sensors
Explain thermal switch system
- heat sensitive units that complete electrical circuits at a set temperature
What are the thermal switch indicator lights connected in
Series
How does the thermal switch system work
- if temp rises above set value
- thermal switch closed
- completing circuit to indicate a fire or overheat conditions
Explain thermocouple system
- depends on rate of temp rise
- does not give warning when engine slowly overheats (or short circuit)
thermocouple wiring system is divided into the following
- Detector circuit
- alarm circuit
- test circuit
What are optical sensors referred as
- flame detectors
What are the 2 types of optical sensors
- Infrared (IR) (used on light turboprop and helicopter engines)
- Ultraviolet
What is the sensing element in pneumatic detectors
- closed helium filled tube
How is the average temperature sensing activated
- expansion of a fixed volume of helium gas inside the detector
What are the 2 continuous loop detector systems
- Fenwal
- Kidde
What does the fenwal system use
A slender Inconel tube
When fire has been extinguished in fenwal, what occurs
- automatically returns to standby alert ready to detect any subsequent fire/overheat condition
In a fenwal what does an overheat condition produce
Resistance of eutectic salt within the sensing elements drop sharply
Explain kidde continuous loop system
- 2 wires embedded in an Inconel tube filled with thermistor core material
- one conductor has ground connection
- other conductor connects to the fire detection control unit
Explain dual loop systems
- 2 complete fire detection systems
- 2 signals required for a fire signal for reliability
What do the fire extinguisher containers store
- Liquid halogenated extinguishing agent
- and pressurised gas (nitrogen)
What are the fire bottle containers made out of
Stainless steel
Red disc thermal blow out indicates what
Thermal blow out
Yellow disc blow out indicates what
- flight crew activated fire extinguishing system
- requires replacing
What happens when fire switch is activated
- engine stops because fuel control valve closes (engine isolated)
- fire extinguishing system is armed
