Fire Protection
GENERAL
The fire protection system includes provisions for fire detection and extinguishing in the following areas:
Engines and firewalls.
APU.
Fire detection only is provided for the following area:
Wheel wells.
Overheat detection only is provided for the following areas:
No. 1 and No. 3 engine struts.
Lower aft body, which includes the pneumatic ducts between the cabin floor and aft cargo compartment ceiling and pneumatic ducts on the keel beam.
ENGINES AND FIREWALLS
DETECTION
A heat rise sensed by the detector in any engine or firewall will
Sound the fire bell,
Iight its engine fire handle, and
Illuminate both pilots‘ master FIRE WARN lights.
The following will turn off the appropriate fire warning indications while the fire condition exists:
Pressing the BELL CUTOUT will silence the bell.
Pressing either master FIRE WARN light will extinguish both pilots‘ FIRE WARN lights and
Location
Fire warning lights (fire handles), the bell cutout switch and the test switch are located on the center glareshield panel. Pressing either master fire warning light will silence the bell and extinguish both master fire warning lights.
(1) Bottle Discharge Handles Pull to discharge selected bottle. (2) Bottle Transfer switch Select corresponding bottle. (3) Bottle Discharge Lights. Illuminate if selected bottle is empty. (4) Fire Test Switch Checks integrity of fire protection system and illuminates the two master fire warning lights, three engine fire warning lights and causes the fire alarm bell to ring.
(5) Bell Cutout Switch When pushed, silences fire alarm bell, APU warning horn and extinguishes both master fire warning lights.
EXTINGUISHING
Fire control is effected by shutting off fuel, hydraulic fluid, bleed air and the engine generator with the fire handle and by discharging a fire bottle.
Fire Bottles
Two fire bottles containing an extinguishing agent under pressure, provide a means of combating engine and firewall fires. The fire bottles are located in the right hand airstair area. Either bottle can be discharged to any engine.
Fire Handles
When an engine fire handle is pulled:
The fuel shutoff valve closes.
The bottle discharge butto is armed.
The engine selector valve is armed.
The generator field relay is tripped.
The engine bleed air valves are closed for
Airconditioning
Wing anti-ice
Eng No. 2 inlet anti-ice.
The corresponding No. 1 or No. 2 hydraulic fluid shutoff closes.
Bottle Discharging
When the armed bottle discharge button is pressed that engine’s selector valve opens and discharges freon from the fire bottle selected by the BOTTLE TRANSFER switch. The freon causes the yellow discharge disc tob e ejected, and then flows tot he engine to smother the fire. Amber discharge lights on the engine fire control panel will illuminate to indicate BOTTLE DISCH when the respective bottle has been discharged.
The remaining fire bottle may be discharged into the same engine by moving the transfer switch tot he opposite position and again actuating the same discharge button.
AUXILIARY POWER UNIT
DETECTION
A heat rise detected within the APU shroud:
Rings the fire bell.
Lights the cockpit APU fire handle.
Illuminates both pilots‘ master FIRE WARN lights.
Shuts down the aPU (when the AUTO FIRE SHUTDOWN switch is in the ARMED position).
EXTINGUISHING
Primary fire control is accomplished by sshutting off APU fuel with the fire handle. Secondary fire control is effected by discharge of a fire bottle to combat any remaining fire. Normally, aPU shutdown occurs automatically if a fire is detected.
The freon bottle, in the left wing fillet area can be discharged from the cockpit. Pulling the APU fire handle in the cockpit:
Arms the bottle discharge switch.
Closes the APU fuel shutoff valve.
Closes the APU bleed air valve.
Trips the APU generator field relay and generator relay.
Pressing the armed BOTTLE DISCHARGE button discharges freon into the APU shroud.
ENGINE STRUT AND LOWER AFT BODY OVERHEAT
DETECTION
The No. 1 and No. 3 engine struts and the lower aft body, which includes the keel beam and the area above the aft cargo compartment, contain heat sensing elements. A heat rise in any of these areas will light ist respective warning light on the flight engineer’s panel.
EXTINGUISHING
There is no fire bottle provided to combat an overheat condition. The only corrective action available is to reduce or turn off bleed air.
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