(b)  
Apply anti-seize compound to the threads of the elbows (8 and 11).

 (c)  
Install the fittings in the precooler pressure sense port and the downstream pressure sense port.

 (2)
Install the ground stud (20) on the PRSOV (AMM 20-11-15/401).

 S 214-017

 (3)  
Examine the two seals (5) for damage.

 (a)  
Replace the damaged seals.

 S 434-016
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747-400 MAINTENANCE MANUAL
 (4)  S 434-018Remove the covers from the ducts.
 (5)  S 434-019Install a seal (5) in each duct flange.
 S 424-039

 CAUTION: DO NOT HOLD THE TEMPERATURE SENSOR PROBE OF THE PRSOV DURING
_______ THE PRSOV REMOVAL OR INSTALLATION. DAMAGE TO THE PROBE COULD OCCUR.
 (6)
Put the PRSOV (1) in position between the duct flanges.

 S 434-021

 (7)
Install the two couplings (4) loosely.

 S 644-040

 (8)
Apply anti-seize compound to the threads of the elbows (8 and 11).

 S 824-022

 (9)  
Turn the PRSOV (1) until the elbows (8 and 11) align with their tubes (6 and 7).

 NOTE: Make sure that the manual override drive aligns with the hole
____ in the access door. If the valve is not aligned correctly, it will prevent use of the manual override tool, which can cause a maintenance delay.
 S 434-023
 (10)
 Tighten the couplings (4) to 110-125 pound-inches (12-13 N.m).

 S 434-024

 (11)
 Connect the precooler pressure sense tube (6) to the elbow (8).

 S 434-040

 (12)
 Connect the downstream pressure sense tube (7) to the elbow (11).

 S 434-025

 (13)
 Connect the bonding jumper (2) to the PRSOV (1). (AMM 20-11-15/401).

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747-400 MAINTENANCE MANUAL
 S 764-026
 (14)
 Make sure that the resistance between the ground stud (20) on the PRSOV and the airplane structure is less than 0.005 ohms (AMM 20-22-01/601).

 S 434-027

 (15)
 Connect the electrical connector (3) to the PRSOV (1):

 (a)  
DV83 - PRSOV ENGINE 1

 (b)  
DV85 - PRSOV ENGINE 2

 (c)  
DV86 - PRSOV ENGINE 3

 (d)  
DV87 - PRSOV ENGINE 4

 S 864-028
 (16)
 For the applicable engine, remove the DO-NOT-CLOSE tags and close these circuit breakers:

 (a)  
P6 Main Power Distribution Panel
 1) 6H32 AIR SUPPLY CONT ENG 1
 2) 6H33 AIR SUPPLY CONT ENG 2
 3) 6H34 AIR SUPPLY CONT ENG 3
 4) 6H35 AIR SUPPLY CONT ENG 4

 S 794-029
 (17)
 Apply the leak detector to the valve flanges and to the tube connections.

 S 864-043

 (18)
 Make sure the PRSOV position indicator is not in the locked closed position.

 S 794-030

 (19)
 Dry motor the engine (AMM 71-00-00/201):

 S 214-041

 (20)
 Make sure that the PRSOV position indicator moves to the open position.

 S 794-042

 (21)
 Examine the tube connections and valve flanges for leakage:

 (a)  
Repair the cause of any leakage from the tube connections.

 (b)  
If bubbles come slowly into view around the valve flanges, the amount of leakage is satisfactory.

 (c)  
Repair the cause of the leakage if there is a high
 concentration of leakage from the valve flanges.

 S 414-031
 (22) Install the access doors on each side of the strut (AMM 06-09-09/201).
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