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King Air Ground School. 26 - Fire Protection. Overview. Engine Fire Detection, IR Detection System Not on E90 Engine Fire Extinguishing – Halon based fire extinguishing Not on U21 or E90 Portable Extinguisher – at least one halon in the cockpit Overheat protection for Bleed air
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King Air Ground School 26 - Fire Protection
Overview Engine Fire Detection, IR Detection System Not on E90 Engine Fire Extinguishing – Halon based fire extinguishing Not on U21 or E90 Portable Extinguisher – at least one halon in the cockpit Overheat protection for Bleed air Emergency Portable Breathing Devices
Sensors / Detectors Infrared photocells
Sensors / Detectors 3 Sensors in each engine compartment Each sensor looking at a different zone in the engine compartment 1-forward of intake 2-upper accessory case 3-lower accessory case Zone 1 Zone 3 Zone 2
Amplifier-Controller Amplifier-Controller translates sensor detection to cockpit annunciations Amplifier-Controller allows for testing the system Illustration shows the relationship between sensor/detector and amplifier-controller L Engine Fire Detected No fire detected
Annunciators U21A “LH/RH FIRE WARNING” and “FAULT WARN” U21H “FIRE L/R ENG” and “MASTER WARNING” U21H U21A
Annunciators C12 T-handle – “#1/2 FIRE PULL” and “MASTER WARNING” 200 “FIRE L/R ENG” and “L/R ENG FIRE-PUSH TO EXT” and “MASTER WARNING” C12 200
Test Switch U21 – 8 position switch “Test Switch Fire Detection” C12 – 6 position switch “Fire Protection Test” 200 – 7 position switch “Test Switch Fire Det & Fire Ext” Only turn counter clockwise unless the test fails U21 200 C12
Electrical Circuit Breaker in Cockpit – with CB pulled, detection won’t work Dual-fed bus – power must be on the aircraft in order to detect 200 U21 C12
Test The three DET/DETR positions of the test switch Position 1 tests the fwd intake sensor of both engines Position 2 tests upper accessary case sensor of both engines Position 3 tests lower accessory case sensor of both engines Position 1 Position 3 Position 2
Test Sensors are tested by increasing the output voltage of each sensor
Test U21A and U21H Both “LH/RH FIRE WARNING” / “FIRE L/R ENG” annunciators illuminate “FAULT WARN” / “MASTER WARNING” is triggered Audible warning horn U21A U21H
Test C12 Both T-handle “#1/2 FIRE PULL” annunciators illuminate “MASTER WARNING” is triggered C12
Test 200 Both “FIRE L/R ENG” annunciators illuminate “MASTER WARNING” is triggered “L/R ENG FIRE PUSH TO EXT” light on both sides 200
Fire Indication An actual fire has the same indications but will only be on the side of the fire U21A U21H 200 C12
Referenced Procedures Engine Fire/Failure/Severe Damage Evacuation/Engine Fire on the Ground U21 C12
Toxicity Not highly toxic but does cause issues in high concentrations (>10%) Typical side effects include giddiness and tingling of extremities Same chemical family as Freon No extinguishing area
Aviation Uses 1301 used commonly for engine extinguishing 1211 or blend commonly used for portable fire extinguishers Portable Engine Extinguishing
Extinguishes Fire By: Chemically combining with atoms which are propagating the fire, preventing combustion reaction (primary) Displaces oxygen (secondary) Cools the fire (secondary)
Fire Extinguishing Bottle One bottle per engine Discharges through plumbing to nozzles into fire zones
Fire Extinguishing Bottle Pressure provides the motive flow for the halon Fully discharges in .08 seconds Zone 2&3 nozzles Zone 1 nozzles
Pressure Gauges Pressure indicates quantity of halon available Gauge visible from the wheel well Ambient temperature determines the pressure limits Aft Looking up, LH Main
Squibs Pyrotechnic squib cartridge holds plug in place “firing” the squib releases the plug Halon flows to the discharge nozzles
Annunciations C12 Red “PUSH TO EXTINGUISH” indicates squib is armed Indicates squib has discharged
Annunciations 200 Indicates a fire is detected Indicates squib has discharged
Actuation C12 Pull appropriate T-Handle Lift clear cover Push the annunciator to discharge the bottle Only fires the bottle that has been armed by the T-Handle
Actuation 200 Lift clear cover Push the appropriate annunciator to discharge the bottle One switch per side
Test Switch Two remaining positions of the rotary test switch 200 C12
Electrical Hot battery bus – bottles can be discharged with the batt master off
Test EXTGH portion of rotary switch Tests the circuitry to the squib and discharge light C12 “#1/2 EXTGH DISCH” and “SQUIB OK” C12 #1 & 2
Test EXTGH portion of rotary switch Tests the circuitry to the squib and discharge light 200 “D” and “OK” 200
Push to Extinguish Pull T-Handle Lift clear cover Press the “PUSH TO EXTINGUISH” button Look for “#1/2 EXTGH DISCH” annunciator C12 LH extinguish
Push to Extinguish Lift clear cover Press the “L/R ENG FIRE PUSH TO EXT” button Look for “D” annunciator 200 LH extinguish
Bleed Air Supply Line Hot bleed air from engine is delivered to cabin P3 air leaves the engine at 640⁰F A broken line threatens smoke and fire
Heat Sense Line Pressurized, plastic line runs along side bleed air lines 18psi originates at pneumatic controller At 204⁰F the plastic line melts
Pressure Switch (C12/200) One for the LH and RH sense lines Below 18psi, this switch closes to warn the pilot Pressure switch located under co-pilot seat
Pressure Switch (U21) There are two pressure switches one for each side located just before the check valves.
Annunciator Light (C12/200) “L/R BL AIR FAIL” and “MASTER WARNING” The pressure switches illuminate these annunciators respectively 200 C12
Annunciator Light (U21) “LH/ RH BLD AIR FAIL” and “MASTER WARNING” U21 A U21 H
Bleed Air Line Rupture C12/200 The hot air melts the sense line (and anything else around it) The low volume pressure in the sense line escapes Pressure switch closes at18psi “L/R BL AIR FAIL” annunciator Illumes with “MASTER WARNING” A loss of pressure in the sense line indicates a serious threat 200 C12
Bleed Air Line Rupture U21 If a break in the bleed air line should occur the air pressure in the line would drop causing the pressure switch to open and the “LH or RH BLD AIR FAIL” to illume.
Referenced Procedures • C12 • U21