(a)  
If there is damage, make sure the damage or wear is within the permitted limits (AMM 28-22-07/601).

 S 212-096
 (2)
Do these steps to check the installation of the fuel couplings:

 (a)  
Make sure the O-rings are new and are not contaminated or damaged.

 (b)  
Make sure the O-rings are lubricated with petrolatum before the installation.

 (c)  
Make sure the retaining rings are new and are not deformed or bent.

 (d)  
Make sure all of the coupling components are installed and in the correct sequence.

 (e)  
Make sure the coupling is manually tightened.

 (f)  
Make sure the coupling is tightened as far as possible by hand.

 D.
Procedure

 S 432-011
 (1)  Put the coupling nut on the ferrule on the tube A.
 S 432-012
 CAUTION:_______DO NOT CAUSE THE RING TO BE OUT OF ITS CORRECT SHAPE. IT CAN CAUSE PERMANENT DAMAGE TO THE RING AND RESULT IN LEAKS AT THE COUPLING.
 (2)  
Put a retaining ring on the ferrule to keep the nut on tube A.

 S 432-013

 (3)  
Install a new O-ring, lightly lubricated with petrolatum, in the groove in the body installed on tube B.

 S 432-014
 CAUTION:_______DO NOT USE TOOLS TO TIGHTEN THE FUEL LINE FITTINGS. YOU CAN CAUSE POSSIBLE DAMAGE TO THE FITTING COMPONENTS OR LOOSEN THE ADJACENT FITTINGS.
 (4)  
Align tubes A and B and tighten the coupling nut with your hand.

 (5)  
Put a lockwire through the nut to the ferrule.

 S 432-033
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A
747-400 MAINTENANCE MANUAL
 S 432-043 CAUTION: YOU CANNOT TIGHTEN THE FUEL LINE COUPLING AFTER THE INITIAL
_______ INSTALLATION. YOU MUST INSTALL NEW O-RINGS WHEN YOU TIGHTEN THE FUEL LINE COUPLING AGAIN OR A FUEL LEAK CAN OCCUR.
 (6)  If you must tighten the fuel line coupling again, disconnect the fuel line coupling and install new O-rings.
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A
747-400 MAINTENANCE MANUAL
COUPLING NUT
LOCKWIRE
A
A
O-RING  BODY
RETAINING RING A-A
COUPLING NUT TUBE B
O-RING
FERRULE
TUBE A

EXPLODED VIEW
RIGID COUPLING
Fuel Tube Coupling Installation
Figure 201 (Sheet 1)

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LINE B 
BODY 
RETAINING RING  FERRULE 
COUPLING NUT  BODY  LINE A  ASSEMBLED VIEW 
FERRULE 

A
747-400
MAINTENANCE MANUAL

COUPLING NUT EXPLODED VIEW
FLEXIBLE HALF COUPLING
Fuel Tube Coupling Installation Figure 201 (Sheet 2)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
COUPLING NUT
C
COUPLING

C
O-RINGS COUPLING NUT
TUBE B
COUPLING
FERRULE
FERRULE
FERRULE
TUBE A
ASSEMBLED VIEW
　
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