S 644-047
 WARNING: DO NOT USE TITANIUM FITTINGS IN THE OXYGEN SYSTEM TUBING.
_______
 FITTINGS CAN CAUSE A FIRE OR INJURY TO PERSONS.

 CAUTION:_______DO NOT USE TITANIUM FITTINGS IN OXYGEN SYSTEM TUBING. TITANIUM AND TITANIUM ALLOYS ARE OXYGEN REACTIVE. IF A NEW TITANIUM SURFACE IS OPENED TO GASEOUS OXYGEN, SPONTANEOUS COMBUSTION CAN OCCUR AT LOW PRESSURES.
 (3)  Apply the thread compound applicable to your system (Table 1) (Fig. 401). Apply the thread compound immediately before installation. Apply to the circumference of the external threads, shoulder, and conical seal surface of the flareless sleeve.
 NOTE: Do not get the thread compound in the interior of the tube or
____ the bore of the fitting. Do not apply thread compound when you assemble dri-lubed B-nuts.
 NOTE: It is recommended that titanium or steel fittings be used as
____ replacements for aluminum fittings in the high pressure and normal brake return systems between the antiskid module and parking brake module. Titanium or steel fittings may be used as replacements for aluminum fittings in other systems.
 S 424-010
 (4)  
Put the tubing assembly in the airplane and keep the tube clamps loose to permit you to align the tube in the fitting.

 S 214-042

 (5)  
Look at the tags to make sure the tubes are aligned with the correct port fittings.

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747-400
MAINTENANCE MANUAL

 S 824-011
 (6)  
Align the tube and fitting by hand and make the tube end touch the bottom of the fitting.

 S 434-012

 (7)  
Keep the tube end at the bottom and aligned in the fitting. Turn the B-nut by hand until the B-nut touches bottom on the sleeve shoulder.

 S 434-013

 (8)  
To tighten the assembly, hold the union with a wrench and torque tighten the B-nut to the recommended value (Fig. 403).

 NOTE:____Do not use the B-nut to align the tube. Do not let the B-nut touch the bottom.
 S 434-014
 CAUTION:_______ALWAYS KEEP THE CLAMPS TIGHT. TIGHT CLAMPS KEEP THE AREA BETWEEN THE TUBE AND THE CLAMP SURFACES FREE OF UNWANTED MATERIALS AND CONTAMINATION. IF SURFACES ARE NOT CLEAN, ABRASION CAN OCCUR.
 (9)  Tighten by hand the nuts which you cannot get access to torque tighten. Hand tighten until a clear increase in torque occurs, then tighten 1/6 to 1/3 (one or two hex flats) turn more.
 NOTE: The maximum tube collapse permitted after you torque the
____ BACS13AP sleeves is 0.015 inch less than the tube diameter (Fig. 402).
 S 434-015
 (10)
 Tighten all the tube clamps.

 S 714-043

 (11)
 If you disconnected more than one hydraulic tube and you think there is a possibility you connected the tubes incorrectly or cross-connected the tubes, do an operational check:

 NOTE: Use your own judgement to determine if a check is necessary.
____
 (a)  Do the post-installation test of one or more components to which the tubes are connected as a check.
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747-400 MAINTENANCE MANUAL
 S 714-044
 (12) If you disconnected electrical wires to get access to the tubes and you think there is a possibility you connected the wires incorrectly or cross-connected the wires, do an operational check:
 NOTE: Use your own judgement to determine if a check is necessary.
____
 (a)  Do the post-installation test of one or more components to which the wires are connected as a check.
 S 794-031
 (13) Do a leak test:
 (a)  
Pressurize the system for 5 minutes minimum.

 (b)  
With the system pressurized, rub the tube and fitting with a clean white cloth to find leakage.

 NOTE: You can tighten again to the torque value specified
____ above, if you find leakage. If leakage occurs in subsequent leak tests, you must replace appropriate parts.
　
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