Module 15.20 Fire Protection Systems Flashcards
What is a fire zone?
An area of the aircraft designated to require fire detection, extinguishing equipment, and a high degree of fire resistance.
What are thermal switches?
Heat-sensitive units that complete electrical circuits at a set temperature.
What does a thermocouple depend on?
Rate of temperature rise
When would a thermocouple not give a reading?
When an engine slowly overheats or a short circuit develops.
What does the thermocouple do if the temperature rises rapidly
Produces a voltage.
When are optical sensors designed to alarm?
When they detect the presence of specific radiation emissions from hydrocarbon flames.
What are the two types of optical sensors?
Infrared (IR) and ultraviolet
What two sensing functions does a pneumatic thermal fire detector have?
It responds to an overall average temperature threshold and to a localised discrete temperature increase.
What sensing system do commercial aircraft use?
Continuous thermal sensing elements.
What two types continuous thermal systems are used?
Kidde and Fenwal
What is the Kidde continuous loop system?
Two wires are embedded in an Inconel™ tube filled with a thermistor core material.
What is the Fenwal continuous loop system?
A slender Inconel™ tube packed with thermally sensitive eutectic salt and a nickel wire centre conductor.
What are dual loop systems?
Two complete fire detection systems with their output signals connected so that both must signal to result in a fire warning.
How many extinguisher discharges must an aircraft have?
Two
What is a single shot exinguisher system used on?
APUs
What extinguisher agent is used?
Halon 1301
What do fire extinguisher containers store?
A liquid halogenated extinguishing agent and pressurised gas
What shape are most aircraft extinguisher bottles?
Spherical
When are cylindrical fire bottles used?
Where space limitations are a factor.
Where is the squib and frangible disc type valve installed?
The outlet of the discharge valve assembly.
What type of gauge is available on fire bottles
Visual indicated gauge. Typically a vibration-resistant helical Bourdon-type indicator.
What does a combination gauge do?
Indicates actual container pressure and provides an electrical signal if container pressure is lost.
When is a two-way check valve needed?
In a two-shot system.
What does a two-way check valve do?
Prevents the agent in the reserve container from backing up into the previously emptied main container.
What do discharge indicators do?
Provide immediate visual evidence of container discharge
When does a red disc indicator discharge?
When container contents have been dumped overboard due to excessive heat.
When does a yellow disc indicator discharge?
If the flight crew activates the fire extinguisher.
Where are fire switches typically installed?
On the centre overhead panel or centre console in the flight deck.
How is the flight crew alerted of a fire?
Visible and audible warning systems.
What are the two types of turbine failure
Thermodynamic
Mechanical
What is a spot fire detection system?
A system with individual sensors to monitor the fire zone.
Optical sensors can sometimes be referred to as what?
Flame detectors
What two types of sensing can pneumatic detectors use?
Average and discrete temperature sensing.
