B. Prepare for Seal Replacement
(1)
Check that ground lock assemblies are installed on nose and main landing gears (Ref 32-00-01).
(2)
Depressurize hydraulic systems.
(3)
Operate brakes eight times to depressurize brake accumulator.
(4)
Open all landing gear circuit breakers on panel P6.
(5)
Deflate shock strut (Ref 12-15-31) by removing valve cap from charging valve at top of shock strut. Loosen outer hexnut two turns maximum.
WARNING: DO NOT LOOSEN VALVE BODY UNLESS SHOCK STRUT IS COMPLETELY DEFLATED. AIR PRESSURE CAN BLOW VALVE BODY OUT, CAUSING INJURY TO PERSONNEL.
CHARGING VALVE MUST REMAIN OPEN. INTERNAL PRESSURE CAN BLOW OUT GLAND NUT AND INJURE PERSONNEL.
(6) Place a container under shock strut, remove check valve and drain oil from strut. When shock strut is empty, install check valve.
NOTE: Arrow on check valve points up when check valve is installed.
C. Replace Seals with Spare Seals
(1)
Measure and record the distance the gland nut (12) extends below the outer cylinder (17) for use in subsequent step (Fig. 801, Detail B).
(2)
Place cloth padding around shock strut inner cylinder below gland nut (12) to prevent sharp edge of hole in gland nut from damaging inner cylinder if gland nut is accidently allowed to slide down inner cylinder when unscrewed from outer cylinder.
(3)
Place drip tray to catch hydraulic fluid when gland nut is removed.
CAUTION: CLEAN ANY HYDRAULIC FLUID FROM TIRES IMMEDIATELY, SHOULD ANY SPLASH ON THEM, TO AVOID DETERIORIZATION.
(4)
Remove gland nut lock plate (1) on aft side of shock strut.
(5)
Use gland nut wrench to unscrew gland nut and slide nut to bottom of inner cylinder.
(6)
Jack airplane and slide scraper adapter (11) and scraper ring (10) down inner cylinder onto removed gland nut.
(7)
Continue jacking and work out lower bearing (7), washer (6), and seal adapter (4).
(a) Examine outside diameter of lower bearing. If corrosion is present or coating is damaged, remove shock strut (Ref Removal/Installation) and replace bearing.
(8)
Cut active static seal O-ring (3) and backup rings (15) from outer groove in seal adapter (4). Use a plastic tool to prevent damage to adapter.
(9)
Cut active dynamic seal (21), cut channel seal (5) or remove backup rings (5) from inner cylinder.
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32-11-21 Page 802 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Aug 01/96
CAUTION: EXTREME CARE MUST BE EXERCISED AS ANY NICKS OR SCRATCHES ON INNER CYLINDER, BESIDES DAMAGE TO THE INNER CYLINDER ITSELF, WILL DAMAGE THE SEAL ADAPTER AS THEY SLIDE OVER THE DAMAGED SURFACE OF THE INNER CYLINDER.
NOTE: When cutting active seal or channel seal; use backup metal strip between seal and surface of material which seal contacts.
(10)
Slip spare static seal O-ring (9) from lower spare seal recess in lower bearing (7) and apply a coat of MIL-H-6083 hydraulic oil and a light coat of petrolatum prior to installation.
(11)
Carefully stretch lubricated spare static seal O-ring only enough to install O-ring in groove of seal adapter (4, Fig. 801) and install a new backup ring on each side of O-ring.
NOTE: O-rings must have no twists when installed.
(12)
Slip a spare dynamic seal O-ring or seal assembly (8) from upper spare seal recess in lower bearing (7) and apply a coat of MIL-H-6083 hydraulic oil and a light coat of petrolatum prior to installation.
(13)
Coat a cam seal if installed with petrolatum.
(14)
Slide spare dynamic seal O-ring or seal assembly up inner cylinder into recess in seal adapter. Position cam seal immediately below dynamic seal O-ring, if installed.
(15)
Slide lower bearing (7) against newly positioned cam seal, if installed, to hold seal and newly installed O-ring or seal assembly in place and slide bearing and seal adapter as a unit into outer cylinder.
(16)
Slide scraper adapter (11) with scraper ring (10) into position against lower bearing.
(17)
Slide gland nut (12) into position to screw into outer cylinder.
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Jan 20/83 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 32-11-21 Page 803
CAUTION: GLAND NUT AND OUTER CYLINDER THREADS MAY HAVE BEEN REWORKED (OVERSIZE). IF SO, GLAND NUT AND OUTER CYLINDER SHOULD BE IDENTIFIED ACCORDINGLY AND KEPT AS A SET.
NOTE: If trouble is experienced in moving lower bearing into outer cylinder, align inner cylinder and place a wooden block of equal dimensions on each side of inner cylinder below gland nut and jack inner cylinder until nut reaches outer cylinder.
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