(a)  
Use the manual handle to close all of the crossfeed valves (AMM 28-22-01/401).

 (b)  
If you need to leak check the other fuel system manifolds, then continue with these procedures: 1) Refuel/Jettison Manifold - Leak Check 2) CWT Interconnect Manifold - Leak Check

 (c)  
If you do not need to leak check the other manifolds, then do this procedure: Put the Airplane Back to the Usual Condition.

 S 786-219
 (12) If the results show the pressure decreased more than 1.5 psi
 (10.3 kPa) in 10 minutes, then there is a leak in the engine fuel-feed line.
 (a)  Do this procedure: Repair the Leak in the Fuel System Manifold.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-22-07
 ALL  ú ú 02 Page 625 ú Jun 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 H. Refuel/Jettison Manifold - Leak Check
 S 786-220
 (1)  
Make sure the leak check of the engine fuel-feed manifold is satisfactory.

 S 786-221

 (2)  
Open these fuel station access doors:

 (a)  
521BB, Fueling Station Access Door

 (b)  
621BB, Fueling Station Access Door

 S 786-222
 (3)  
Open these valves (left and right wing):

 (a)  
Manual defuel valves

 (b)  
Manual shutoff valves (two locations on each wing)

 S 786-190
 (4)  
Put the manual handle on FUEL CROSSFEED VALVE NO. 2 to the OPEN position.

 S 786-192

 (5)  
Use the air pressure source to apply 5 psig (34 kPa) to the
 refuel/jettison manifold.

 S 786-223

 (6)  
After the pressure stabilizes, increase the pressure to 40 psi (275 kPa).

 S 786-224

 (7)  
Close the shutoff valve on the test equipment.

 S 786-225

 (8)  
Monitor the pressure gage.

 S 786-226

 (9)  
After 10 minutes record the indicated pressure from the pressure gage.

 S 786-227

 (10)
 Open the bleed valve slowly and let the pressure in the lines bleed to zero.

 (a)  
Put a container next to the bleed port on the test equipment to capture any fuel leakage.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-22-07
 ALL  ú ú 02 Page 626 ú Jun 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 786-264
 (11) If the pressure remained the same or decreased by less than 3.0 psi
 (20.7 kPa) in 10 minutes, then the manifold is satisfactory.
 (a)  If the manifold is satisfactory, then do these steps: 1) Put the manual handle of FUEL CROSSFEED VALVE NO. 2 to the CLOSED position (AMM 28-22-01/401).
 2)  If it is necessary to leak check the CWT interconnect manifold, then do this procedure: CWT Interconnect Manifold - Leak Check
 3)  If you are done with the leak checks, then do this procedure: Put the Airplane Back to the Usual Condition.
 S 786-229
 (12)
 If the pressure decreased more than 3.0 psi (20.7 kPa) in 10 minutes, then there is a leak in the refuel/jettison manifold.

 (a)  
Do this procedure: Repair the Leak in the Fuel System Manifold.

 I.  
CWT Interconnect Manifold - Leak Check

 S 786-230
 (1)  
Make sure the leak check of the engine fuel-feed manifold is satisfactory.

 S 786-231

 (2)  
Make sure the leak check of the refuel/jettison manifold is satisfactory.

 S 786-232

 (3)
Manually put these valves to the OPEN position (AMM 28-31-04/401):

 (a)  
Left CWT jettison transfer valve

 (b)  
Right CWT jettison transfer valve

 S 786-233
 (4)  
Open these valves located at the pressure refuel stations (left and right wing) (if not previously opened):
　
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