1. King Air Ground School
26 - Fire Protection

2. 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
Infrared means “below red” in the electromagnetic spectrum (energy)
Photocells (sensors) turn IR energy into electron flow
Controller/Amplifier senses current flow- if threshold exceeded, it creates annunciations
3 photocells per engine

3. Engine Fire Detection: Components

4. Sensors / Detectors Infrared photocells
Photocells induce electron flow when exposed to infrared radiation
Infrared means “below red” in the electromagnetic spectrum (energy)
Controller/Amplifier senses electron flow- when threshold is exceeded, it creates annunciations

5. 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
3 photocells per engine
Not a smoke detector
Zone 1
Zone 2
Zone 3

6. 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
Controller/Amplifier senses current flow- when threshold is exceeded, it creates annunciations
No fire detected
L Engine Fire Detected

7. Annunciators U21A “LH/RH FIRE WARNING” and “FAULT WARN”
U21H “FIRE L/R ENG” and “MASTER WARNING”
U21A
U21H

8. 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

9. 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
C12
200

10. 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
U21
200
C12

11. Engine Fire Detection: Operation

12. Test The three DET/DETR positions of the test switch Position 1
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 2
Position 3

13. Test
Sensors are tested by increasing the output voltage of each sensor
Sensors are tested by increasing the output voltage of the sensor to a sufficient level to signal the amplifier as if a fire is present.
Clear the master between each test position to check master warning is triggered.
Test should be done at a deliberate pace. Running quickly through each test position isn’t a valid test.

14. 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

15. Test C12 C12 Both T-handle “#1/2 FIRE PULL” annunciators illuminate
“MASTER WARNING” is triggered
C12

16. Test 200 200 Both “FIRE L/R ENG” annunciators illuminate
“MASTER WARNING” is triggered
“L/R ENG FIRE PUSH TO EXT” light on both sides
200

17. Fire Indication
An actual fire has the same indications but will only be on the side of the fire
U21A
U21H
C12
200

18. Referenced Procedures
Engine Fire/Failure/Severe Damage
Evacuation/Engine Fire on the Ground
U21
C12

19. Engine Fire Detection: Abnormalities
False Fire Indication
Sun light/ reflections
Water/ moisture in sensor/wiring
Bad sensor

20. Halon

21. 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

22. Aviation Uses 1301 used commonly for engine extinguishing
1211 or blend commonly used for portable fire extinguishers
Portable
Engine Extinguishing

23. Extinguishes Fire By:
Chemically combining with atoms which are propagating the fire, preventing combustion reaction (primary)
Displaces oxygen (secondary)
Cools the fire (secondary)

24. Engine Fire Extinguishing: Components

25. Fire Extinguishing Bottle
One bottle per engine
Discharges through plumbing to nozzles into fire zones
One pressurized halon 1301 bottle for each engine, located in wheel wells
Discharges through plumbing to nozzles into all fire zones for that engine not the intake

26. Fire Extinguishing Bottle
Pressure provides the motive flow for the halon
Fully discharges in .08 seconds
Bottle will fully discharges in .08 seconds
Discharges into fire zones, not intake
Zone 2&3 nozzles
Zone 1 nozzles

27. Pressure Gauges Pressure indicates quantity of halon available
Gauge visible from the wheel well
Ambient temperature determines the pressure limits
Aft
Pressure indicates quantity of halon available
-low pressure indicates loss of halon - servicing required
Gauge visible from the wheel well
-Orientation is different between the L and R wheel well
Minimum pressure chart should be referenced
-pressure will be different for the same quantity of halon at different temperatures
Looking up, LH Main

28. Squibs Pyrotechnic squib cartridge holds plug in place
“firing” the squib releases the plug
Halon flows to the discharge nozzles
Bottle will fully discharge in .08 seconds

29. Annunciations C12 Red “PUSH TO EXTINGUISH” indicates squib is armed
Indicates squib has discharged

30. Indicates a fire is detected
Annunciations
200
Indicates a fire is detected
Indicates squib has discharged

31. Only fires the bottle that has been armed by the T-Handle
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

32. Actuation 200 Lift clear cover
Push the appropriate annunciator to discharge the bottle
Both buttons are always armed
One switch per side

33. Test Switch
Two remaining positions of the rotary test switch
C12
200

34. Electrical
Hot battery bus – bottles can be discharged with the batt master off

35. Engine Fire Extinguishing: Operation

36. 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

37. Test EXTGH portion of rotary switch
Tests the circuitry to the squib and discharge light
200 “D” and “OK”
200

38. 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

39. Push to Extinguish Lift clear cover
Press the “L/R ENG FIRE PUSH TO EXT” button
Look for “D” annunciator
200 LH extinguish

40. Bleed Air Overheat Protection: Components

41. 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
Examples of materials that can cause smoke or fire with a bleed air leak
MIL-H-5606 flash point around 200°F
Zipties give way at 185⁰F
5606 flashpoint: 200⁰F
Kydex burns at 400⁰F
Though bleed air is very hot, at normal restricted flow rates it will become somewhat stagnant in the lines, allowing it to cool significantly in the lines. If there is a leak, the faster flow allows less time to cool in the lines. This will lead to hotter realized bleed air temps spilling out of the damaged line.

42. Heat Sense Line
Pressurized, plastic line runs along side bleed air lines
18psi originates at pneumatic controller
At 204⁰F the plastic line melts
Typically blue plastic line running alongside bleed lines
Uses same bleed air it is monitoring to pressurize the line
-Pressure is significantly reduced to 18 psi by the pneumatic regulator
Bleed air used for monitoring pressure is significantly cooler due to
-Length of run from engine source to pneumatic regulator
-Significant reduction of pressure (114 psi to 18 psi)
-Lack of actual flow in pressurized line (Bleed air does not flow through the sense line, it only pressurizes it (like a garden hose that is turned on at the house but the nozzle is closed)
Melting temp of the plastic sense line is 204°F

43. Pressure switch located under
Pressure Switch (C12/200)
One for the LH and RH sense lines
Below 18psi, this switch closes to warn the pilot
Located at the end of the sense line opposite to the pressure source
One switch per side
Closes electrical contacts at or below 18psi, open above 18psi
Pressure switch located under
co-pilot seat

44. Pressure Switch (U21)
There are two pressure switches one for each side located just before the check valves.
Located on a standoff pipe at the end of the bleed air line near the mixing valve. Senses pressure within the bleed air supply line

45. Annunciator Light (C12/200)
“L/R BL AIR FAIL” and “MASTER WARNING”
The pressure switches illuminate these annunciators respectively
C12
200

46. Annunciator Light (U21) “LH/ RH BLD AIR FAIL” and “MASTER WARNING”
U21 A
U21 H

47. Bleed Air Overheat Protection: Operation

48. 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
When bleed air is ported to the supply line, the heat sensing line is pressurized with a very small volume of bleed air (not enough to heat it up)
The heat sensing line is a closed line with no flow. Bleed air pressurizes the line only.
If a bleed air supply line begins to leak, the hot air will melt the plastic sensing line, sense line pressure drops triggering the pressure switch
Loss of pressure lights the “L and R BL AIR FAIL” annunciator
C12
200

49. 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.

50. Referenced Procedures

51. Duct Overtemp Protection: Components

52. Between FO rudder peddles
Temperature Switch
Senses air temperature
Located in mixing plenum of the U21
Located in the duct after of mixing plenum of the C12/200
Located aft of where the hot and cold are mixed together
U21
Between FO rudder peddles
C12/200
RH Mid cabin

53. Annunciator
“DUCT OVERTEMP”
C12
U21A
U21H
200

54. Duct Overtemp Protection: Operation

55. Air Temp in Duct Rises
Air in the ducting becomes too hot (potential for smoke)
Temperature switch closes circuit (225°F -300°F)
“DUCT OVERTEMP” annunciator illumes
U21A
C12
Air temp in duct reaches 225°F -300°F
Light illuminates
Pilot must correct by increasing cold air volume or reducing hot air volume (will be discussed in bleed air system)
U21H
200

56. Referenced Procedures

57. Portable Fire Extinguishers

58. Halon blend (2:1)
Located under pilot seat and an optional second one could be mounted in the cabin

59. Portable Breathing Devices

60. PBE Part 25
Part 25 required
Fixed (stationary, or built in) protective breathing equipment must be installed for the use of the flightcrew, and at least one portable protective breathing equipment shall be located at or near the flight deck for use by a flight crewmember. In addition, portable protective breathing equipment must be installed for the use of appropriate crewmembers for fighting fires in compartments accessible in flight other than the flight deck.

61. EPOS Components EPOS - Model MR-10096AF Hood
-The hood is a multi-layer design of polyimide film and PFA film, which provides excellent resistance to most chemicals. It measures 13 inches at its circular base, and is 19 inches high, with an internal volume of approximately 23 liters (slightly less than 1 cubic foot).
-The EPOS hood’s ability to withstand fire is limited
-EPOS hood can withstand a 1000°C (1,832°F) flame for five seconds without burning through.
-The EPOS hood can withstand radiant heat of 1.0 BTU/sq. ft. for up to 60 seconds.
Neck Seal
-The neck seal is a high strength, highly elastic silicone rubber design that fits all adult sizes with an 11 to 19 inch neck without adjustment.
Oxygen System
-One cylinder of compressed Aviator’s Grade Oxygen at 3,000 psi, with an equivalent ambient volume of approximately 18 liters, is mounted on the bottom side of the neck seal.
Carbon Dioxide Scrubber
-Carbon dioxide is a natural byproduct of respiration. Because the EPOS is a closed circuit system, it is necessary to remove the carbon dioxide that builds up inside the hood. This is accomplished with a passive chemical scrubber. The average carbon dioxide concentration will be kept below 4% for the duration of use, but may reach a momentary peak of 7%.
Humidity Indicator
-Humidity indicator to indicate integrity of EPOS packaging for preflight purposes, if the humidity indicator is blue the unit is serviceable. If the humidity indicator is pink, the unit is to be replaced.

62. EPOS Operation 1. OPEN CLOSURE FLAP OF STOWAGE POUCH.
2. GRASP STOWAGE POUCH W/ ONE HAND AND WITH OTHER HAND PULL RED TAPE STRIP OF BARRIER POUCH.
3. REMOVE THE EPOS UNIT FROM BOTH POUCHES.
In the process of donning the unit, the user must grab the oxygen cylinder in one hand and the red ball in the other in order to pull the hood open. The red ball is tethered to the oxygen seal on the bottle. Pulling the hood open pulls the red ball apart from the bottle which pulls the oxygen seal off of the bottle starting the flow of oxygen. The force required to pull the seal off is approximately 12 pounds.
4. PULL THE RED BALL WITH ONE HAND WHILE HOLDING THE OXYGEN CYLINDER WITH THE OTHER HAND.

63. 7. REMOVE HOOD AFTER YOU ARE CLEAR OF HAZARD
EPOS Operation
5. SPREAD NECK SEAL OPEN WITH HANDS. PALMS ARE TO BE FACING EACH OTHER.
6. PULL THE EPOS OVER THE HEAD.
Even though the flow of oxygen stops after five minutes, there is sufficient oxygen inside the hood for the escape situations shown in the “Duration of Use”
-Duration of Use: All emergency rescue and escape situations are different, and it is not possible to provide an exact duration time for all situations. Also, the size of the EPOS user will affect usable life, with heavier individuals consuming oxygen more rapidly. However, for an average male, the following typical escape situations are useful in predicting how long the EPOS will last
-Sitting, waiting to be rescued -Up to 60 minutes
-Waiting 17 minutes to be rescued, then rapid evacuation -Up to 21 minutes
-Moderate walking (3 mph) -Up to 18 minutes
-Rapidly walking, on a flat, out of a building -Up to 8 minutes
-Rapidly walking up 15 flights of stairs -Up to 3 minutes
When the unit deflates to the point where it touches the wearer’s head and face, the unit’s useful life has ended and must be removed
7. REMOVE HOOD AFTER YOU ARE CLEAR OF HAZARD

64. PBE Training Video