(3)  
Slide the clock from the panel.

 (4)  
Disconnect the electrical cable.

 S 024-004
 S 034-005
 TASK 31-25-01-404-006
 3.  Clock Installation__________________
 A. References
 (1)  
24-22-00/201, Manual Control

 (2)  
AIPC 31-25-00, Fig. 1 (Clocks)

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 B. Access
 (1)  Location Zone
 221 Flight Compartment, Left
 222 Flight Compartment, Right

 C. Procedure
 S 864-007
 (1)  Make sure that these circuit breakers are open:
 (a)  P6 Main Power Distribution Panel
 1) 6H08 ELEX CLOCK
 2) 6H17 CLOCK DISP

 S 434-008
 (2)  
Connect the electrical cable to the clock.

 S 424-009

 (3)  
Slide the clock into the panel.

 S 434-010

 (4)  
Tighten the mounting screws of the clamp.

 S 714-018

 (5)  
Do a test of the clocks:

 (a)  
Provide the electrical power (Ref 24-22-00/201).

 (b)  
Remove the DO-NOT-CLOSE tags and close the circuit breakers that follow: 1) P6 Main Power Distribution Panel

 a) 6H08 ELEX CLOCK
 b) 6H17 CLOCK DISP

 (c)  
Set the clock to Greenwich Mean Time (GMT) with the SET switch.

 (d)  
Set the DATE on the clock with the push-button switch.

 (e)  
Make sure that the clock operates for not less than 2 minutes.

 (f)  
Make sure that the time and the date are satisfactory.

 (g)  
Remove the electrical power if it is not necessary (Ref 24-22-00/201).

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 31-25-01
 ALL  ú ú 01 Page 402 ú Jun 10/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
 FLIGHT DATA RECORDER SYSTEM - DESCRIPTION AND OPERATION
_______________________________________________________
 1.  General_______
 A.  The flight data recording system records selected flight parameters received during the last 25 hours of airplane operation.
 B.  The system consists of a Digital Flight Data Acquisition Card (DFDAC), a Flight Data Recorder (FDR), and an accelerometer (Fig. 1).
 C.  The FDR receives the flight data and stores it in solid state memory.
 D.  The FDR is turned on automatically by the DFDAC when any of the following conditions are true: when the AIR/GND relay is in the air position, when any engine is starting or running, or when a command for a Power-up Test is received from the Central Maintenance Computer (CMC).
 E.  Monitor circuits within the FDR and DFDAC provide fault signals to the EFIS/EICAS Interface Units (EIU) where a status message is generated for display on EICAS.
 F.  The DFDAC receives operating power from the two Modular Avionics and Warning Electronics Assembly (MAWEA) power supply units. The FDR receives 115 volt ac from AC BUS 3 through the FLT REC AC circuit breaker on P415 Power Distribution Center - Right.
 2.  Digital Flight Data Acquisition Card (DFDAC)____________________________________________
 A.  The DFDAC conditions all input signals to produce a digital output data stream for recording by the DFDR. The DFDAC is programmed to output this data in one of five different configurations. These configurations are selected by program pin connections on a MAWEA chassis connector below the DFDAC.
 B.  The DFDAC is in the MAWEA card file located in the right crawlway ahead of the main equipment center. The DFDAC is normally powered, 5 volts dc and |12 volts dc, by two MAWEA power supply units. No loss of capability occurs if powered by only one of the two power supply units.
 C.  The DFDAC receives playback data from the FDR and outputs this data to both the CMC and Data Management Unit (DMU). Additional outputs provided by the DFDAC are an analog discrete output to the FDR Power Control relay and a FDR System BITE (Built-In Test Equipment) status discrete to the EIUs.
　
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