(f)
Loosen the oxygen line connections (if needed), and bleed off the pressure.
S 912-068
(2) Do the oxygen system maintenance:
(a)
Loosen the fitting connections slowly with a back-up wrench to prevent damage to the fitting.
(b)
Remove the manifold hose assembly (Fig. 201, 202, and 203)
NOTE: When the oxygen box is removed the sleeve on the hose
____ connection may stick to the union connection. If the B-nut is disengaged in this condition, it can press against the ferrule, and damage the hose.
1) Loosen the coupling nut but not more than one complete turn.
FERRULE UNION
Hose Assembly Flareless Fitting
Figure 203
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(d)
(e)
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747-400 MAINTENANCE MANUAL
2) Hold the ferrule and the union (Fig. 203), and put a side load on the fitting at approximately 90° to the hose centerline.
NOTE: This will break the sleeve loose.
____
3) Disengage the B-nut.
Use caps and plugs when disconnecting oxygen components.
1) Install the clean caps or plugs immediately into the open
fittings and the ports.
NOTE: You can use new plastic caps if the cap does not
____ engage the connector threads. Use clean metal caps if the cap engages the connector threads.
2) Seal the polyethylene bags that contain the remaining caps and plugs .
NOTE: Do not open the bag until the caps and plugs are
____ to be used. Seal the bags immediately to prevent contamination to the remaining caps and plugs.
Install the manifold hose assembly (Fig. 201, 202, and 203).
1) Align the ferrule with the union.
2) Make sure that the sleeve is fully bottomed against the
fitting.
3) Start the B-nut with your fingers.
4) Use a backup wrench to prevent rotation and possible
damage.
CAUTION: DO NOT TIGHTEN THE OXYGEN HOSE MORE THAN 35 TO 45
_______ POUND-INCHES THIS CAN CAUSE THE SLEEVE CONNECTION TO STICK.
5) Tighten the B-nut until it bottoms against the sleeve
shoulder. 6) Torque to standard torque values (AMM 20-51-01/201).Install the quick-disconnect coupling in the passenger oxygen supply (low pressure hoses)(Fig. 202)
CAUTION:_______DO NOT FORCE FITTINGS TOGETHER. CHIPPED OR SLICED O-RINGS WILL LEAK. DO NOT USE TUBE ASSEMBLIES IF PROTECTIVE PACKAGE IS PUNCTURED AND/OR PROTECTIVE CAPS ARE REMOVED. THE TUBE ASSEMBLIES MAY BE DAMAGED OR CONTAMINATED AND NO LONGER USEABLE IN THE OXYGEN SYSTEM.
1) Align the rigid tube to rigid tube/flex hose
(quick-disconnect coupling) less than two degrees of
centerline.
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CAUTION:_______ LUBRICATE THE O-RINGS WITH KRYTOX 240AC ONLY. IF YOU DO NOT DO THIS IT CAN CAUSE DAMAGE TO THE O-RINGS.
2) Inspect the O-ring to make sure no damage has occured in the installation.
3) 4) Use white cotton gloves when you install the the O-ring on the internal end fittingDo not remove the lubricant from the O-ring.
CAUTION:_______ MAKE SURE TO ENGAGE THE COUPLING TO THE SECOND DETENT OR THE COUPLING CAN EASILY COME LOOSE AND FALL OFF
WHEN NOT CORRECTLY LOCKED. FAILURE OF PASSENGER
OXYGEN MASKS TO DROP IN THE ZONE COULD OCCUR.
5) Slide the hose or tube ends together slowly, do not force them together.
NOTE:____ Quick disconnect couplings snap over the hose assemblies. When you install the coupling, two detents (or points of resistance) can be felt, with the second detent locking the coupling in position.
(f) (g) (h) 6) Make sure the latch pawls are totally engaged after the installation of the retaining device. 7) Visually do a check of the coupling to make sure it is correctly locked to the second detent.Install only the components that are clean.If the component is not clean, discard the component, and install a clean component.When you install a component, start all connectors with your hand.
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