(a)  Make sure there are no air leaks in the hose or the fittings.

(4)  
Connect F80166-1 hose assembly to F71329 leak tracing device.

NOTE:  F71329 leak tracing device is used only to adjust and control application of pressure or vacuum to relief valve.

(5)  
Connect the air supply to the F71329 device.

C.  Do the Pressure Check
(1)  
Slowly apply increasing positive pressure to the test fixture until the relief valve opens as detected by sound and/or manometer level suddenly equalizing.

(a)  Make sure the relief valve stays closed from 0-4 inches of water total manometer displacement (0-0.144 psig pressure gage change/0-1.0 kPa pressure gage change) and opens between 4 and 16 inches of water (0.144-0.557 psig/1.0-3.98 kPa).

(2)  
Turn off the pressure and remove the test fixture from the relief valve.

(3)  
Manually reset the relief valve to closed position (Ref par. 2.B.).

(4)  
Re-install the test fixture on the relief valve.

(5)  
Slowly apply increasing negative pressure (vacuum) to test fixture until relief valve opens as detected by sound and/or manometer level suddenly equalizing.

(a)  Make sure the relief valve stays closed from 0 to -55.4 inches of water total manometer displacement (0 to -2.0 psig pressure gage change/0 to -15.7 kPa pressure gage change) and opens between -55.4 and -74.8 inches of water (-2.0 to -2.70 psig/-13.8 to -18.6 kPa).

(6)  
Turn off the vacuum source.

D.  Put the Airplane Back to Its Usual Condition
(1)  
Disconnect the pressure gage or manometer and leak tracing device and remove them from the area.

(2)  
Remove the test fixture from the relief valve and re-install the four regular mounting screws. Stow the fixture.

(3)  
Manually reset the relief valve to the closed position (Ref par 2.B.).

533 
28-13-41 Page 604  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/03 

CENTER TANK FUEL SCAVENGE SYSTEM - DESCRIPTION AND OPERATION
EFFECTIVITY
AIRPLANES WITH CENTER TANK FUEL SCAVENGE SYSTEM
1. General (Fig. 1)
A.  A fuel scavenge system is installed to decrease the unusable quantity in the center tank by approximately 15 gallons. A fuel scavenge shutoff valve, a jet pump and a fuel flow indicator are mounted on tank No. 1 front spar. A pickup line is routed into the center tank. On ALL EXCEPT airplanes incorporating SB 28-1074, a fuel scavenge shutoff valve and a jet pump are connected to the pickup/transfer line and are mounted on the front spar of tank No. 1. On airplanes incorporating SB 28-1074, a fuel scavenge shutoff valve and a jet pump are connected to the pickup/transfer line and are mounted on the pickup/transfer line in the center tank.
2.  Fuel Scavenge Shutoff Valve
A.  An electrically controlled fuel scavenge shutoff valve controls the flow of fuel from the tank No. 1 boost pumps to the fuel scavenge jet pump to siphon fuel from the center tank.
3.  Fuel Scavenge Jet Pump
A.  The fuel scavenge jet pump creates a low pressure in the fuel scavenge pickup line when tank No. 1 boost pumps pass fuel thru the jet pump. The jet pump siphons fuel from the center tank into tank No. 1.
4.  Fuel Scavenge Fuel Flow Indicator/Check Valve (On ALL EXCEPT airplanes incorporating SB 28-1074)
A.  The fuel flow indicator check valve has a window which is visible from outside tank No. 1. The indicator needle in the blue band indicates no fuel flow. The indicator needle in the green band indicates normal fuel flow. The indicator needle in the red band indicates marginal fuel flow. Marginal fuel flow condition will exist when either the center tank fuel level is below the fuel scavenge pickup (air in scavenge pickup line), or when there is a component failure.
5.  Fuel Scavenge Flapper Check Valve (On airplanes incorporating SB 28-1074)
A.  The flapper check valve located in the center tank pickup/transfer line has a flapper gate which prevents fuel from transferring back into the center wing tank.
Feb 20/89 28-15-0 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

Center Tank Fuel Scavenge System Component Location  500 
28-15-0  Figure 1 (Sheet 1)  Feb 20/89 
Page 2 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

6.  Operation
A.  When both center tank boost pumps are turned off, the fuel scavenge shutoff valve is opened, and a 20-minute timer in the M528 engine accessory unit is started.
NOTE:  Fuel will be scavenged from the center tank into tank No. 1 during this 20 minute time period only.
　
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