20-10-09
ALL ú ú 01.1 Page 821 ú Sep 28/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
S 438-286
(3) Use tape to make a mark on the tube to make sure you put the Cryofit
coupling over the center of the tube repair.
(4) S 328-287Cut the tube.
(5) S 118-288Chamfer and remove burrs from the ID and OD edges. with solvent, Series 80 (AMM 20-30-80/201). Clean the edges
S 948-289
WARNING:_______USE EXTREME CARE WHEN USING LIQUID NITROGEN. THE TEMPERATURE OF LIQUID NITROGEN IS 320 DEGREES BELOW ZERO. PROVIDE PROPER VENTILATION AS LIQUID NITROGEN VAPORS CAN DISPLACE OXYGEN IN CONFINED AREAS. USE SAFETY GLASSES, A FACE SHIELD, AND INSULATED GLOVES WHEN USING LIQUID NITROGEN. MISSUSE OF LIQUID NITROGEN CAN CAUSE INJURY TO PERSONS.
(6)
Put on the insulated gloves, the safety glasses, and the face shield.
S 948-290
(7)
Put liquid nitrogen (-320°F) into a small, insulated container.
S 948-291
WARNING: SLOWLY AND CAREFULLY SUBMERGE WARM ITEMS IN LIQUID NITROGEN TO
_______ PREVENT RAPID BOILING OFF AND SPLASHING. MISSUSE OF LIQUID NITROGEN CAN CAUSE INJURY TO PERSONS.
(8)
Remove the Cryofit coupling from the main storage container and put it into the small container of liquid nitrogen. Make sure the coupling is fully covered by theliquid nitrogen.
S 948-292
(9)
Move the Cryofit coupling in the liquid nitrogen (-320°F) to the repair location.
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20-10-09
ú ALL ú
ú ú ú 01.101 ú BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. Page 822Sep 28/02
A
757
MAINTENANCE MANUAL
S 948-293
(10)
Put the tongs and the tube chiller into the small container of liquid nitrogen.
S 438-294
(11)
Slip the test coupling (from the installation kit) over the tube ends to ensure that tubes are round and free of burrs. The test coupling should slide freely.
S 438-296
(12)
Remove the test coupling and place the marking gauge over one of the tube ends. Using the marking pen, color in the rectangular slot in the gauge to provide an installation mark on the tube. Follow the same procedure to mark the remaining tube end.
S 438-297
(13)
Place an installation stop ("O" ring) or snap on coupling in the middle of the mark on one of the tube ends. Check the location by positioning the test coupling so that it is butted against the stop. Both tube ends should be visible in the window and the test coupling should cover approximately half the installation mark on each tube. Adjust the tubes and installation stop as necessary. Remove the test coupling.
S 438-298
(14)
Ensure that the tube ends, within half the coupling length of the end, are free of scratches. If a fitting must be installed over a tube end containing a scratch, apply a thin layer (one to two drops) of Loctite 290 around the tube circumference in the area under the serrations. Be careful not to let the Loctite into the tube. No Loctite application is required for tube ends without scratches.
S 438-300
(15)
Place the cooled tube chiller over the tubes to be joined. Remove the chiller after 20 to 30 seconds.
NOTE:____This step may be omitted. However, placing the Cryofit coupling in contact with a tube which has not been pre-chilled with liquid nitrogen may initiate premature warming and shrinkage of the coupling.
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