(d)  
Use the APU to pressurize the pneumatic system (AMM 36-00-00/201).

 (e)  
Put the APU BLEED switch to the ON position. 1) Make sure the valve (1) moves to the OPEN position.

 (f)  
Examine the valve flanges for leakage. 1) If bubbles come slowly into view, the quantity of leakage is satisfactory.

 2)  If bubbles come quickly into view, or if jet blast leakage occurs, you must repair the cause of the leakage.

 (g)  
Stop the operation of the APU (AMM 49-11-00/201).

 (h)  
Release the pressure in the pneumatic system (AMM 36-00-00/201).

 E.  Put the Airplane to Its Usual Condition
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A
747-400 MAINTENANCE MANUAL
 S 094-032
 WARNING: YOU MUST CAREFULLY DO THE STEPS IN THE TASKS BELOW TO REMOVE
_______ THE DOOR LOCKS ON THE LANDING GEAR DOORS. THE DOORS CAN CLOSE QUICKLY IF YOU DO NOT REMOVE THE DOOR LOCKS CORRECTLY. THIS CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT.
 (1)  
Do this task: "Removal of the Door Locks on the Wing Landing Gear" (AMM 32-00-30/201).

 S 094-045

 (2)  
Do this task: "Removal of the Door Locks on the Body Landing Gear" (AMM 32-00-30/201).

 S 414-033

 (3)  
Close the doors for the wing and body landing gear (AMM 32-00-30/201).

 S 864-034

 (4)  
Remove the electrical power if it is not necessary (AMM 24-22-00/201).

 TASK 36-11-09-204-039
 4. Do a Visual Check of the APU Isolation Valve
____________________________________________
 A. References
 (1)  
AMM 36-00-00/201, Pneumatic System

 B.
Access

 (1)  
Location Zone
 137A Body Landing Gear Wheel Well, LH

 C.
Procedure

 S 864-040
 (1)  
Open this circuit breaker on the main power distribution panel, P6 , and attach a DO-NOT-CLOSE tag:

 (a)  
6H22 APU ISO VLV AIR SUPPLY PWR

 S 214-041
 (2)  Do a visual check of the APU isolation valve and the electrical connections.
 NOTE: You will examine the valve and the electrical connections
____ for the correct installation and for the condition.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 864-042
 (3)  
Remove the DO-NOT-CLOSE tag and close this circuit breaker on the main power distribution panel, P6:

 (a)  
6H22 APU ISO VLV AIR SUPPLY PWR

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 PNEUMATIC GROUND CONNECTION CHECK VALVE - REMOVAL/INSTALLATION
______________________________________________________________
 1.  General_______
 A.  This procedure contains two tasks. The first task removes the check valve for the pneumatic ground connection. The second task installs the check valve for the pneumatic ground connection.
 B.  There are two check valves for the pneumatic ground connection installed on the airplane. They are installed aft of the door for the aft left air conditioning bay. It is necessary to open the door for the air conditioning bay to get access to the valves.
 TASK 36-11-14-004-001
 2.  Remove the Check Valve for the Pneumatic Ground Connection (Fig. 401)__________________________________________________________
 A.  References
　
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