Engine Fire Extinguishing System Component Location
Figure 1 (Sheet 2)

B20574
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MAINTENANCE MANUAL

 C. Squib Test Panel
 (1)  The squib test panel is located on the P61 right side panel. The switches on the panel are used to check extinguisher bottle squib cartridges. When pressed, the test switch on the panel checks circuit continuity through the squib cartridges. A green test light comes on for a successful test.
 3. Operation (Fig. 2)
_________
 A. Functional Description
 (1)  
When a fire is detected in an engine, the appropriate fire switch handle red warning light comes on. A solenoid energizes releasing a mechanical interlock on the handle shaft. The handle is then operable. The mechanical interlock is manually released by pressing the button located behind the handle. When an engine fire switch handle is pulled out, the extinguishing bottles are armed for that engine. The following also happens: the engine generator field relay and generator circuit breaker are tripped, the engine fuel shut-off valve closes, the fire bell is reset, the engine drive hydraulic pump is depressurized, the engine hydraulic pump supply shut-off valve closes, the air supply pressure regulating and shut-off valve closes, the SPAR valve closes, the engine fuel shut-off valve shuts off, and the electrical power to the T/R control system is removed. The APU shut-off valve closes only when the LEFT engine fire handle is pulled. When the LEFT engine fire handle is pulled, only the pneumatic supply from the APU is shut off, not the APU.

 (2)  
After pulling a fire switch handle out, rotating it discharges the extinguishing agent into the appropriate engine compartment. Rotating the handle counterclockwise discharges bottle number 1. Rotating it clockwise discharges bottle number 2. Decreasing bottle pressure, by discharge or leakage, activates the pressure switch. The switch sends a signal which turns on the appropriate amber ENG BTL DISCH light. The ENG BTL 1 and 2 DISCH lights are on the engine fire control panel P8. After a decrease in bottle pressure is recognized, an ENG BTL 1 or 2 DISCH message appears on the EICAS display.

 (3)  
Engine fire extinguishing agent can be discharged to either engine compartment from either bottle. Tubing runs from the bottles through the forward wing spars to each engine compartment. Extinguishing agent discharges from outlet nozzles in the forward and aft section of the engine compartment.

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MAINTENANCE MANUAL

SQUIB TEST
L ENG R

APU
1212

AFT CARGOFWDTEST
1212

L SQUIB01
L SQUIB
FIRE EXT

G BOTTLE 1 BOTTLE 2
RIGHT
ENG 2 LT

BTL 2 ENG R
R
SQUIB
G
FIRE EXT

R SQUIB28V DC
PRESSURE
RIGHT
BTL 1 ENG RSWITCH
HOT BAT ENG 1 LTBUS RSQUIB
G
PFIRE EXT
TO LEFTENGINE
LEFT
BTL 2 ENG L
UP ENG 2 LT
L SQUIB
AFT WWBULKHEAD G
PRESSUREFIRE EXTFIRE EXT
TO RIGHT FWD
SWITCH  BOTTLE 2ENGINE
LEFT
BTL 1 ENG L
(APU)
ENG 1 LT

(CARGO) ENG BOTTLE 2
P6
SQUIB TEST

ENG BOTTLE 1
SWITCH  ENG SQUIBTEST
L ENG ENG BTLENG BTL R ENG OVHT 1 DISCH
2 DISCH OVHT
R EICAS CMPTR
DISCH
DISCH12 12
SQUIB TEST PANEL ENG BOTTLE 2
ENG BOTTLE 1
L EICAS CMPTRDISCH
DISCH12 12
BTLBTL
BLT
1 2 BLT
2 1 P MD & T
ENG BTL
A 2 DISCH
CLOSE APU AIR
CLOSE ENG BLEED
CLOSE ENG BLEED
AIR VALVE

SPARE
SUPPLY VALVE AIR VALVE
PRESSURE SWENG BOTTLE 2 DISCH LIGHT
SPARE
ELEX WARNENG FUELELEX WARNCOND CONT
CLOSE FUELENGINE FUELTHRUST REVCLOSE FUEL MD & T VALVE
COND CONTOVERRIDE VALVE ENG BTL
A 1 DISCH
CLOSE HYDRAULICTHRUST REVCLOSE HYDRAULIC
　
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