WARNING: OBEY THE INSTRUCTIONS IN THE PROCEDURE TO OPEN THE THRUST
_______ REVERSERS. IF YOU DO NOT OBEY THE INSTRUCTIONS WHEN YOU OPEN THE THRUST REVERSERS, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR.
 (7)  
Open the left thrust reverser (AMM 78-31-00/201).

 S 014-012

 (8)  
Disconnect the PRSOV-pressure-sense tube (6) and the PRV-controller-precooler-pressure-sense hose (9) from the tee (30) (Fig. 401, Sheet 2).

 NOTE: The tee (30) is located on the forward lower left corner of
____ the precooler.
 S 034-013
 (9)  
Disconnect the bracket (5) from the precooler exhaust flange.

 S 034-014

 (10)
 Remove the two couplings (7) from the ducts upstream and downstream of the precooler (1).

 S 944-015

 (11)
 Put the protective mat under the precooler (1) to prevent damage to the fuel manifold.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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A
747-400 MAINTENANCE MANUAL
 S 034-016
 WARNING: BE CAREFUL WHEN YOU REMOVE THE PRECOOLER BECAUSE THE PRECOOLER
_______ WEIGHS APPROXIMATELY 112 POUNDS (51KG). IF YOU DROP THE PRECOOLER, IT CAN CAUSE DAMAGE TO THE ENGINE FUEL MANIFOLD OR INJURIES TO PERSONS.
 (12) Do the steps that follow to loosen the mounting bolts (15 and 22) and the nuts (10 and 19) for the preecooler (Fig. 401, Sheet 3).
 NOTE: Make sure all of the mounting bolts move freely before you
____
 remove one of them.

 (a)  
On the upper corner of the aft left side of the precooler, loosen the upper right bolt (15) and the nut (10).

 (b)  
On the lower corner of the aft left side of the precooler, loosen the bolt (15) and the nut (10).

 (c)  
On the upper corner of the forward left side of the precooler, loosen the bolt (22).

 (d)  
On the lower corner of the aft right side of the precooler, loosen the bolt (15) and the nut (10).

 S 034-017
 (13)
 Do the steps that follow to remove the four mounting bolts for the precooler:

 (a)  
On the upper corner of the aft left side of the precooler, remove the upper right bolt (15), washer (14), bushing (13), washer (11), and nut (10).

 (b)  
On the lower corner of the aft left side of the precooler, remove the bolt (15), washer (14), bushing (13), washer (11), and nut (10).

 (c)  
On the upper corner of the forward left side of the precooler, remove the bolt (22) and washer (21).

 (d)  
On the lower corner of the aft right side of the precooler, remove the bolt (15), washer (14), bushing (13), washer (11), and nut (10).

 S 024-018
 (14)
 Remove the precooler (1) from the strut right side.

 (a)  
Remove the seals (8) from the duct flanges.

 S 034-019
 (15)
 If it is necessary to replace the precooler, remove the fittings from the precooler (Fig. 401, Sheets 3, 5, and 6).

 (a)  
Remove the two brackets (35 and 37) from the precooler-fan-air inlet.

 (b)  
Remove the tee (33), jamnut (31), O-ring (32), and bracket (34) from the lower corner of the aft right side of the precooler. 1) Discard the O-ring (32).

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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28. SCREW
27. CLAMP (HOLDS TUBE (23))
27. CLAMP (HOLDS TUBE (24))
A
747-400
MAINTENANCE MANUAL

33. TEE (CONNECTS TO TUBE (25 and 26))
28. SCREW
27. CLAMP (HOLDS WIRE BUNDLE)
31. JAM NUT
3. WASHER
29. NUT
34. BRACKET
3. WASHER
32. O-RING
29. NUT
H 29. NUT
3. WASHER
35. BRACKET
27.
 CLAMP
(HOLDS
WIRE BUNDLE)
　
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