28-42-01
 ALL  ú ú 11 Page 404 ú Jun 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 024-025
 WARNING:_______BE CAREFUL WHEN YOU REMOVE THE PRESSURE SWITCH. IF YOU ARE NOT CAREFUL, FUEL CAN DRAIN FROM THE FUEL TANK.
 (10)
 Remove the pressure switch.

 (a)
Discard the O-ring.

 TASK 28-42-01-404-010
 3.  Pressure Switch Installation____________________________
 A. Equipment
 (1)
Bonding Meter - approved for fuel vapor areas (SWPM 20-20-00)

 B.
References

 (1)
AMM 24-22-00/201, Manual Control

 (2)
AMM 27-81-00/201, Leading Edge Flap System

 (3)
AMM 32-00-30/201, Landing Gear Door Locks

 (4)
SSM 28-42-01, 28-42-02

 (5)
WDM 28-42-11, WDM 28-42-12, WDM 28-42-13, WDM 28-42-14

 (6)
AIPC 28-42-01, Fig. 1

 (7)
SWPM 20-20-00, Electrical Bond and Ground

 C.
Access

 (1)  
Location Zones 135 Wing Landing Gear Well, Left 136 Wing Landing Gear Well, Right 521 Leading Edge to Front Spar, Left 571 Rear Spar to Landing Gear Support Beam, Left 573 Rear Spar to Inbd Aileron Leading Edge, Left 621 Leading Edge to Front Spar, Right 671 Rear Spar to Landing Gear Support Beam, Right 673 Rear Spar to Inbd Aileron Leading Edge, Right

 (2)  
Access Panels
 573AT Access Door, Left
 673AT Access Door, Right

 D.
Procedure

 (1)
Install a new O-ring on the pressure switch.

 S 424-012

 (2)
Install the pressure switch.

 (a)
Tighten to a torque of 95-105 pound-inches.

 S 434-011
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 28-42-01
 ALL  ú ú 11 Page 405 ú Jun 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 (b)  Install a lockwire.
 S 424-043
 (3)  Install the electrical connector.
 NOTE: Reference the subsequent table for equipment numbers.
____
 ~................................................................. | | Equipment Number | | Location ............................ | | Switch | Connector | ................................................................... | Boost Pump - No. 1 Main Tank - Fwd | S63 | DS63 | | Boost Pump - No. 1 Main Tank - Aft | S62 | DS62 | | Boost Pump - No. 2 Main Tank - Fwd | S65 | DS65 | | Boost Pump - No. 2 Main Tank - Aft | S64 | DS64 | | Boost Pump - No. 3 Main Tank - Fwd | S70 | DS70 | | Boost Pump - No. 3 Main Tank - Aft | S69 | DS69 | | Boost Pump - No. 4 Main Tank - Fwd | S72 | DS72 | | Boost Pump - No. 4 Main Tank - Aft | S71 | DS71 | | Ovrd/Jett Pump - Ctr Tank - Left | S66 | DS66 | | Ovrd/Jett Pump - Ctr Tank - Right | S68 | DS68 | | Ovrd/Jett Pump - No. 2 Main - Aft | S238 | DS238 | | Ovrd/Jett Pump - No. 2 Main - Fwd | S239 | DS239 | | Ovrd/Jett Pump - No. 3 Main - Aft | S240 | DS240 | | Ovrd/Jett Pump - No. 3 Main - Fwd | S241 | DS241 | | APU Boost Pump | S435 | DS435 | 2......................................…...........…..............1
 S 764-044
 (4)  Measure the electrical resistance between the pressure switch body and structure (SWPM 20-20-00).
 NOTE: The resistance must not be more than 0.050 ohm.
____
 NOTE: The electrical connector must be in place when you do the
____
 bonding measurement.

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 28-42-01
 ALL  ú ú 11 Page 406 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 E. Operational Test
 S 714-045
 (1)  After you install the pressure switch, do the applicable operational test(s) per Table 401.
　
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