(2)  
Access Panels
 3804 APU Cowl Door

 D.  Procedure
 S 034-002
 (1)  
Remove the APU power plant (AMM 49-11-00/401).

 S 024-003

 (2)
Remove the check valve from the fuel heater in the upper shroud:

 (a)  
Put a container below the check valve.

 (b)  
Disconnect the fuel inlet line from the check valve.

 (c)  
Let the fuel in the fuel inlet line drain into the container.

 (d)  
Install a cap on the fuel inlet line.

 (e)  
Remove the check valve from the fuel heater.

 (f)  
Remove the packing from the check valve. 1) Discard the packing.

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////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES /MAINTENANCE MANUAL ////////////////////////
SEE B
SEE  A 
SEE C HEATER FOR THE FUEL CHECK VALVE  UPPER SHROUD  A
FUEL HEATER 

FUEL INLET LINE
CHECK VALVE FOR THE FUEL FWDHEATER
B
FUEL HEATER
C
Fuel Heater Check Valve Installation Figure 401
A98664
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(g) Remove the container with the fuel from below the check valve.
 TASK 49-31-91-404-004
 3. Check Valve Installation (Fig. 401)
________________________
 A. Special Tools and Equipment
 (1)  MS21913-6 Plug
 B. Standard Tools and Equipment
 (1)  Container - for fuel, 5 U.S. gallon (20 liter) capacity
 C. References
 (1)  
AMM 24-22-00/201, Manual Control

 (2)  
AMM 49-11-00/401, APU Power Plant

 D. Access
 (1)  
Location Zones
 703 APU Compartment

 (2)  
Access Panels
 3804 APU Cowl Door

 E. Procedure
 S 424-005
 (1)  Install the check valve to the fuel heater in the upper shroud:
 (a)  
Put a new packing on the check valve.

 (b)  
Install the check valve to the fuel heater.

 NOTE: Make sure the arrow on the check valve points in the
____ direction of the fuel heater.
 (c)  
Remove the cap from the fuel inlet line.

 (d)  
Connect the fuel inlet line to the check valve.

 S 794-006
 (2)  Do a test of the check valve for leakage:
 (a)  
Supply external electrical power to the airplane (AMM 24-22-00/201).

 (b)  
Install the plug to the fuel supply hose.

 (c)  
Set the No. 1 AFT FUEL PUMP switch on the P5 forward overhead panel to the ON position.

 NOTE: If you must use the fuel boost pumps in the
____ center tank, you must have a maintenance person or observer in the flight compartment to continuously monitor the LOW PRESSSURE lights. Turn the applicable fuel boost pump to the OFF position if the LOW PRESSURE light for the center tank stays on.
 (d)  
Manually open the APU fuel valve.

 (e)  
Monitor the check valve to make sure there are no leaks: 1) Put the container below the fuel supply hose. 2) Monitor the check valve for leakage for 5 minutes.

 a) If there is any leakage, repair the cause of it.
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////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES/MAINTENANCE MANUAL ////////////////////////
　
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