(b)  
Open the access panel, 521CB, for the refuel control panel P42, on the left wing.

 (c)  
Make sure the refuel quantity indicators operate correctly.

 (d)  
Move the fuel truck or defueling source into position.

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A
747-400
MAINTENANCE MANUAL

 CAUTION:_______ ATTACH BONDING CABLES ONLY TO SPECIFIED POINTS ON THE
 AIRPLANE.  BONDING CABLES ATTACHED TO COMPOSITE DOORS OR
 FAIRINGS DO NOT GIVE AN ELECTRICAL BOND.  INCORRECTLY
 ATTACHED BONDING CABLES CAN CAUSE SCRATCHES.  THESE
 SCRATCHES CAN CAUSE CORROSION AND CRACKS ON STRESSED

 PARTS.
 (e)  Connect a bonding cable from the defueling source to an approved electrical grounding or bonding connection on the airplane (AMM 20-41-01/201).
 NOTE: If the defueling source has a permanently attached
____ grounding/bonding cable, you can use it here.
 (f)  
Remove the refuel receptacle caps.

 (g)  
Connect the ground cable for the fueling nozzle to the ground jack on the wing.

 NOTE: The ground cable is not necessary if there is electrical
____ continuity between the nozzle and the receptacle.
 (h)  
Lift the LIFT TO DEFUEL lever in each receptacle adapter.

 (i)  
Connect the hose nozzles to the receptacles.

 (j)  
Open the manual defueling valves.

 (k)  
Open the manual shutoff valves for the fueling receptacle.

 S 862-309
 (12)
 To defuel the center wing tank or the inboard main tanks, do these steps:

 (a)  
Open these circuit breakers and attach DO-NOT-CLOSE tags:

 1)  P6 Main Power Distribution Panel a) 6E17 CTR R & MAIN 2 JTSN VLV b) 6F17 CTR L & MAIN 3 JTSN VLV

 (b)  
Open each of these valves with the manual override lever on the valve actuator for each valve (AMM 28-31-04/401): 1) Jettison transfer valve for the No. 2 main tank 2) Jettison transfer valve for the No. 3 main tank 3) Left and right jettison transfer valves for the center wing

 tank.

 (c)  
AIRPLANES WITH A HYDROMECHANICAL SCAVENGE SYSTEM; If it is necessary to defuel the No. 2 or the No. 3 main tanks, remove the applicable fuel strainer(s) (AMM 28-15-00/201):

 NOTE: An unwanted fuel transfer can occur from the center wing
____ tank to the No. 2 and No. 3 main tanks if the fuel scavenge system operates.
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A
747-400 MAINTENANCE MANUAL
 G. Begin the Defueling Procedure
 S 682-414
 (1)  Put these crossfeed valve switches to the ON position:
 NOTE: The switches are found on the fuel management control
____
 module on the pilots' overhead panel, P5.

 (a)  
FUEL X FEED 1

 (b)  
FUEL X FEED 2

 (c)  
FUEL X FEED 3

 (d)  
FUEL X FEED 4

 (e)  
Make sure the flowbars are shown.

 (f)  
Make sure the word VALVE is not shown on the switches.

 S 652-325
 (2)  Set these pump switches to the ON position:
 NOTE: The pump switches are on the fuel management control
____
 module on the pilots' overhead panel, P5.

 NOTE: The override/jettison pumps in the inboard main tank do
____ not operate until you stop the operation of the pumps for the center wing tank.
 (a)  
Override/jettison pumps:
 1) CTR L
 2) CTR R
 3) OVRD 2 MAIN FWD
 4) OVRD 2 MAIN AFT
 5) OVRD 3 MAIN FWD
 6) OVRD 3 MAIN AFT

 (b)  
Main tank boost pumps:
 1) MAIN 1 FWD and MAIN 1 AFT
 2) MAIN 2 FWD and MAIN 2 AFT
　
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