15.20 FIRE PROTECTION ZONES👌🏼 Flashcards
(29 cards)
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
