Chp 3 ( Fire Detection And Suppression) Flashcards
What is the primary purpose of fire detection and suppression in GTE powered helicopters?
To minimize the possibility of an engine fire and ensure immediate detection and rapid extinction of any fire that occurs.
Where are most potential sources of flammable fluids located in GTE powered helicopters?
They are usually isolated from the ‘hot end’ of the engine, located around the compressor casing in a ‘cool’ zone.
What separates the ‘cool’ zone from the ‘hot’ zone in GTE powered helicopters?
A flame proof bulkhead separates the cool zone from the combustion, turbine, and jet pipe area.
What feature do the engine bays have to prevent fire hazards?
Engine bays are divided into compartments by bulkheads made from stainless steel or titanium, acting as firewalls.
What is the importance of rapid fire detection in GTE powered helicopters?
It minimizes the fire period before engine shut-down and the release of the extinguishing agent.
What must a fire detection system avoid to function correctly?
It must avoid giving false fire warnings caused by short circuiting or moisture ingress.
What is the aim of the fire detection system in GTE powered helicopters?
To rapidly detect and provide cockpit indication of a pending or actual fire.
What type of fire detection system is mentioned?
Firewire-continuous wire.
What is Firewire?
Firewire is the sensing element used in the majority of area fire detectors, consisting of a continuous wire detection element about 2 mm in diameter.
The term ‘Firewire’ is an early trade name still widely used.
How does the Firewire operate?
The resistance of the filling material decreases as temperature increases, creating a circuit between the outer casing and the central electrode, which illuminates the cockpit indication.
How is the Firewire installed?
The Firewire element can be easily installed in continuous loops around monitored areas, making it resilient to damage from vibration.
This design allows the wire to operate normally and provide a fire signal even when part of it is defective.
What is a caution regarding Firewire?
Moisture destroys the negative temperature coefficient of the Firewire.
What are the cockpit indications for warnings?
Flashing red lights, Audible warning, Alarm bells
What is the purpose of the test facility on the pilots’ console?
It connects DC to energise a test relay in each control unit to simulate an overheat condition. The detection system actuates the complete cockpit warning system. Releasing the test switch will cancel the warning.
What extinguishant is traditionally used for engine fires?
BCF, charged with nitrogen, although modern eco-friendly gases are being introduced.
Where are the pressurised containers for the extinguishant located?
Outside the fire risk zone.
How is the extinguishant discharged in case of a fire?
It is discharged from the containers through a series of perforated spray pipes or nozzles into the fire.
What components are part of the basic fire suppression system?
Burner manifold, Firewall and fireseal, Multi-way discharge nozzle, Fireproof bulkheads, Bottle-fired indicators, Pressure relief indicators, Fire control handle, First shot, Second shot.
What is the function of the diaphragm in the thermal discharge port?
The diaphragm retains extinguishant until burst by explosion of cartridge.
What are the components of a typical ‘2 Shot’ system operation?
a. A bell, ‘chime’, or other audible alert
b. A flashing ‘attention getter’ light, usually coloured red
c. A FIRE caption on the master warning panel
d. A light in the fire extinguisher operating handle/switch
e. A light in the relevant fuel shut-off or H.P. cock lever.
What is the typical action by the pilot in case of fire?
- Close engine control lever - cut fuel
- Press appropriate extinguisher button
- Low pressure warning light illuminates
- If the ‘FIRE’ light is not out after 15 secs, operate cross feed
- Re-press No 1 button.
What is the function of the Number 1 Engine Fire Extinguisher?
To extinguish fires in the Number 1 engine.
What does the Bottle Low Pressure Warning Lamp indicate?
It indicates low pressure in the fire extinguisher bottle.
What is the purpose of the Test Switch on the Number 2 Engine Fire Extinguisher?
To test the fire extinguisher system.
What should be ensured before working on the fire control system?
Ensure that the electrical power is switched off and disconnect the cartridge leads.
What are the maintenance steps for fire extinguishers?
a. Checking pressure of the extinguishant
b. Weighing fire bottles.
What are the steps for extinguisher removal?
a. Ensure electrically isolated (iaw AMM)
b. Ensure electrically disconnected (iaw AMM)
c. Avionics trade to remove explosive cartridges (iaw AMM)
d. Extinguisher and cartridges to be stored separately
e. Cartridges to be stored in ammo compound (KLP 37.03.07).
