27-51-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 (b)  Make sure the flap indicator bars change to green when the flaps are fully retracted.
 S 862-043
 (5) Do this task to depressurize hydraulic systems No. 1 and 4: "Hydraulic System Depressurization" (AMM 29-11-00/201).
 TASK 27-51-00-862-028
 6. Trailing Edge Flaps Extension with Electrical Power
___________________________________________________
 A. General
 (1)  
There are two control modes to extend the flaps by electrical power: the primary electric mode and the alternate electric mode.

 (2)  
In the primary electric mode, you move the flap control lever to extend the flaps.

 (3)  
In the alternate electric mode, you use the ALTN FLAPS switches on the pilots' center instrument panel to extend the flaps. The flaps will not extend to more than the 25-unit position in the alternate electric mode.

 (4)  
Two of the three flap control unit inputs are from the relays R7774, ALT FLAP INBD TE, and R7775, ALT FLAP 2 OTBD. Circuit breakers TE FLAP ELEC CONT OTBD and TE FLAP ELEC CONT INBD supply power to these relays. If these two circuit breakers are pulled, the flaps will remain in the primary mode. If only one of the circuit breakers are pulled, the flaps will transition into the alternate mode. A FLAPS CONTROL EICAS caution message will be displayed when the flap system is in the alternate mode.

 B.
References

 (1)  
AMM 24-22-00/201, Manual Control

 (2)  
AMM 29-11-00/201, Main Hydraulic Supply System

 (3)  
SSM 27-51-02, 27-51-03

 (4)  
WDM 27-51-21, 27-51-22

 C.
Access

 (1)  
Location Zone
 221, 222 Control Cabin

 D.
Procedure

 (1)
Do this task: "Supply Electrical Power" (AMM 24-22-00/201).

 S 862-024

 (2)  
Make sure hydraulic power is not supplied to systems 1 and 4 (AMM 29-11-00/201).

 S 862-045
 NOTE: The flap system will not operate in primary electric mode
____
 if hydraulic power is supplied.

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
 S 862-031
 WARNING: YOU MUST CAREFULLY DO THE STEPS BELOW TO PREVENT ACCIDENTAL
_______ MOVEMENT OF THE TE FLAPS. THE TE FLAPS CAN MOVE WHEN YOU SUPPLY HYDRAULIC POWER IF THE FLAP ACTUATOR POSITION DISAGREES WITH THE FLAP CONTROL LEVER AND THE ACTUAL FLAP POSITION. MOVEMENT CAN ALSO OCCUR IF ANY OF THE FOLLOWING CIRCUIT BREAKERS ARE OPEN. THESE CIRCUIT BREAKERS PROVIDE THE FLAP CONTROL UNITS (FCU), THE FLAP ACTUATOR AND THE FLAP BYPASS VALVES WITH ELECTRIC POWER.
 (3)  
Make sure these circuit breakers are closed:

 (a)  
On the Overhead Circuit Breaker Panel:
 1) 7C10, FLT CONT ELEC 2L AC
 2) 7C11, FLT CONT ELEC 2L DC
 3) 7C12, FLT CONT ELEC 1L AC
 4) 7C13, FLT CONT ELEC 1L DC
 5) 7C14, FLT CONT ELEC 1R AC
 6) 7C15, FLT CONT ELEC 1R DC
 7) 7C16, FLT CONT ELEC 2R AC
 8) 7C17, FLT CONT ELEC 2R DC

 (b)  
On the Main Power Distribution Panel, P6:
 1) 6E1, PRI TE FLAP CONT AC
 2) 6E2, PRI TE FLAP CONT DC
 3) 6L19, TE FLAP ELEC CONT OTBD
 4) 6L20, TE FLAP ELEC CONT INBD

 (c)  
On the Right Power Distribution Panel, P415:
 1) 415A32, TE FLAP ELEC INBD
 2) 415M38, TE FLAP ELEC OTBD

 S 862-020
 CAUTION: DO NOT OPERATE THE TRAILING EDGE FLAPS WITH ELECTRICAL POWER
_______ THROUGH MORE THAN ONE FULL EXTEND/RETRACT CYCLE IN A 25-MINUTE TIME. THERE WILL BE DAMAGE TO THE FLAP ELECTRIC MOTORS IF YOU OPERATE THEM TOO FREQUENTLY.
 (4)  Extend the flaps in the primary electric mode:
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