(4)  
AIPC 28-21-12 Fig. 1

 (5)  
SSM 28-21-01

 (6)  
WDM 28-21-11, 28-21-12

 D.  
Access

 (1)  
Location Zones 555 Surge Tank, Front Spar to Rear Spar, Left 655 Surge Tank, Front Spar to Rear Spar, Right

 E.  
Procedure

 S 864-024
 (1)  
Open this circuit breaker and attach a DO-NOT-CLOSE tag:

 (a)  
P415 Power Distribution Center
 1) 415M14 FUEL OVERFILL CONT

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-21-12
 ALL  ú ú 01 Page 401 ú Feb 10/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 864-027
 (2)  Supply the electrical power if it is not available (AMM 24-22-00/201).
 S 864-020
 WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF THE LEADING
_______ EDGE AND TRAILING EDGE FLAPS AND FLAP DRIVE MECHANISMS BEFORE YOU MOVE THE FLAP CONTROL LEVER. WITH HYDRAULIC POWER REMOVED, THE FLAPS WILL MOVE AUTOMATICALLY BY ELECTRICAL POWER WHEN YOU MOVE THE FLAP CONTROL LEVER.
 (3)  Extend the leading edge flaps (AMM 27-81-00/201).
 S 494-004
 WARNING: REFER TO AMM 27-81-00/201 FOR THE LOCK INSTALLATION PROCEDURE.
_______ THE FLAPS WILL RETRACT IN 7 SECONDS. INSTALL THE LOCKS TO PREVENT INJURY FROM THE ACCIDENTAL OPERATION OF THE FLAPS.
 (4)  
Install the safety locks in the leading edge flaps (AMM 27-81-00/201).

 S 014-032

 (5)  
Go to the front side of the front spar.

 S 034-005

 (6)  
Disconnect the electrical connector from the float switch receptacle (located on the forward side of the front spar).

 NOTE: Refer to this table for the equipment numbers.
____
 ~.................................................................
 |  |  Equipment Number  |
 | Location .......................... ..
 |  |  Switch  |  Connector  |

 ................................................................... | Surge Tank - Left Wing | S690 | DS690 | | Surge Tank - Right Wing | S691 | DS691 | 2......................................…...........…..............1
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-21-12
 ALL  ú ú 01 Page 402 ú Feb 10/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 144-030
 (7)  
Remove the sealant from the edge of the float switch.

 S 034-006

 (8)  
Remove the nuts and washers (11 locations) which attach the float switch to the forward side of the front spar.

 S 024-007

 (9)  
Remove the float switch.

 NOTE: Turn the switch to clear the opening in the front spar.
____
 S 034-008
 (10)
 Remove and discard the O-ring.

 S 144-034

 (11)
 Remove the old sealant.

 (a)  
Use the sealant removal/application tools (scapers) to remove the old sealant.

 NOTE: The sealant removal/application tools are shown in this
____ task: Repair of Sealant Leaks in the Fuel Tank Structure (AMM 28-11-00/801).
 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR YOUR EYES, OR ON
_______ YOUR SKIN. DO NOT BREATHE THE FUMES FROM SOLVENTS. SOLVENTS ARE HAZARDOUS MATERIALS. SOLVENTS MAY BE FLAMMABLE OR HARMFUL TO THE ENVIRONMENT. REFER TO THE PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
 (b)  
Clean the surface with a clean brush and gauze pads wet with solvents, Series 93 (AMM 20-30-93/201).

 (c)  
Rub the area with a clean, dry gauze pad.

 (d)  
Continue to clean and dry the surface until the dry gauze pad stays clean.

 TASK 28-21-12-404-009
 3.  Wing Surge Tank Float Switch Installation (Fig. 401)_________________________________________
 A. Equipment
　
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