(6)  
When the DISCH button on the fire control module M7327 (P5) is pressed, the bottles A and B are discharged instantaneously. At the same time, the 30-minute time delay in the relay R7454 is activated. If the airplane is still in the air after the time delay is finished, the relay R7454 latches and discharges the bottles C and D. If the airplane reaches the ground before the time delay is finished, the air/ground relay R988 latches and discharges the bottles C and D.

 (7)  
Discharge is by means of electrically fired squibs located in each outlet on the Halon 1301 bottles. There are two discharge outlets on the bottles: one outlet to discharge the agent to the forward lower cargo compartment, and second outlet to discharge the agent to the aft lower cargo compartment.

 (8)  
The condition of the squibs are checked by alternately pressing "TEST" switches and observing the green lights on squib test panel M7327 (P5).

 B.
Lower Cargo Exinguishing System Test

 (1)  
Squib Test

 (a)  The squib test module located on P461 pilots' overhead maintenance panel tests squibs for bottles. The green test indicating lights come on for successful tests.
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 ALL  ú ú 11 Page 8 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 (2)  Pressure Switch Test
 (a)  Manually activating the bottle pressure switch will test the discharge light circuit continuity. Pressing the button located on the switch simulates bottle discharge. The appropriate amber DISCH light will come on and a EICAS message will appear on the EICAS display, indicating a successful test.
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 ALL  ú ú 02 Page 9 ú Feb 10/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
FAULT ISOLATION/MAINT MANUAL

LOWER CARGO COMPARTMENT FIRE EXTINGUISHING SYSTEM
COMPONENT SHT 102 FIG.  QTY  ACCESS/AREA  REFERENCE 
CIRCUIT BREAKERS -M7907,M7908 BOTTLE - CARGO COMPT FIRE EXT M6742,M7906,  2  4 FLT COMPT, P6124, FWD CARGO COMPT  26-23-01 
FIRE EXT LOWER CARGO, C10228  1 6H6 *
 FLT DECK LIGHT CAPT IND, C358 DIODES - (REF 31-01-06, FIG. 101) M3465,M3466,M3467,M3468,M3469,M3470,M3471, M3472  1 6L4  * 
FILTER/DRYER  4  2  FWD AND AFT CARGO COMPT CEILING 26-23-04 
LIGHT - BTL A CARGO, (L5)  1  1 FLT COMPT, P461, SQUIB TEST MODULE, M7327 * 
LIGHT - BTL B CARGO, (L6)  1  1  FLT COMPT, P461, SQUIB TEST MODULE, M7327  * 
LIGHT - BTL C CARGO, (L7)  1  1  FLT COMPT, P461, SQUIB TEST MODULE, M7327 *
LIGHT - BTL D CARGO, (L10)  1  1  FLT COMPT, P461, SQUIB TEST MODULE, M7327 *
MODULE - FIRE CONTROL, M7326  1  1 FLT COMPT, P5  26-21-01 
MODULE - SQUIB TEST, M7327  1  1 FLT COMPT, P461  26-21-02 
REGULATOR RELAY - (REF 31-01-06, FIG. 101) AFT COMPT LOCK IN, R7453 BTL C FIRE EXT METERED DISCH, R7454 SYS ALT AIR/GND, R988 FWD COMPT LOCK IN, R7452  4  2  FWD AND AFT CARGO COMPT CEILING 26-23-03
SQUIB - FWD BTL A  3  1  BTL A, M7906 124, FWD CARGO COMPT, FIRE EXT  26-23-02 
SQUIB - AFT BTL A  3  1  BTL A, M7906124, FWD CARGO COMPT, FIRE EXT  26-23-02 
SQUIB - FWD BTL B 3  1 124, FWD CARGO COMPT, FIRE EXT BTL B, M7907 26-23-02 
SQUIB - AFT BTL B  3  1 124, FWD CARGO COMPT, FIRE EXT BTL B, M7907 26-23-02 
SQUIB - FWD BTL C  3  1 124, FWD CARGO COMPT, FIRE EXT BTL C, M7908  26-23-02 
SQUIB - AFT BTL C  3  1  124, FWD CARGO COMPT, FIRE EXT BTL C, M7908 26-23-02 
SQUIB - AFT BTL D  3  1  BTL D, M6742 124, FWD CARGO COMPT, FIRE EXT  26-23-02
SQUIB - AFT BTL D 3  1  BTL D, M6742 124, FWD CARGO COMPT, FIRE EXT  26-23-02
SWITCH - FWD CARGO FIRE, S1  1  1 FLT COMPT, P5, FIRE CONTROL MODULE M7326 * 
SWITCH - AFT CARGO FIRE, S2  1  1 FLT COMPT, P5, FIRE CONTROL MODULE M7326  * 
　
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