C. Remove aft airstair control console (Ref 52-14-11, Removal/Installation).
D. Remove center and left bulkhead panels from aft cargo compartment aft bulkhead for access to emergency extension mechanism (Ref Chapter 25, Cargo Compartment Bulkhead Lining).
E. Remove pneumatic duct adjacent to emergency extension mechanism. Duct joints are located just forward of the aft pressure bulkhead and just forward of the cargo compartment aft bulkhead. Access to the latter joint requires removal of cargo compartment sidewall lining. Refer to Chapter 25, Cargo Compartment Sidewall Lining, for removal of lining.
G. Remove emergency extension torsion bar (Ref 52-14-31, Removal/Installation).
4. Remove Aft Airstair Drive Emergency Extension Latch and Lockout Mechanism
A. Working from underneath mechanism, remove items located beneath baseplate assembly as follows:
(1)
Remove nut and washer (42, Fig. 401), retaining cap (43), adapter bolt, washer and adapter (44). Remove actuating arm (45) and laminated shims (46).
(2)
Disconnect springs (36, 41) from eyebolts on mounting bracket.
(3)
Remove bolts (32 and 33), latch crank (31), latch arm (38), and latch shaft (34).
NOTE: Note orientation of crank (31) on shaft (34) before removal. Crank can be installed on shaft two different ways. Correct way position bolt (30) washer, nut, and bushing in outboard end of slot in fork link (28).
(4)
Remove nut (40), washers (39), bolt (35), spring (36, 41) and spacers (37) from latch arm (38).
CAUTION: AVOID DAMAGE TO DRY-FILM LUBRICATED SURFACE OF LATCH.
(5)
Remove bolts, washers, and nuts (23, 26 and 30) and remove link (28). Rotate plate assembly for access and remove bolt, washer, and nut (48) attaching link assembly (29) to plate (27) and remove plate (27). Remove pivot link (25).
(6)
Remove nut (15), washer (16) and bolt (14) from latch crank (17) and remove latch crank from latch shaft assembly (21).
(7)
Remove screw and washer (22), latch shaft assembly (21) and splined pivot link (24) from baseplate.
B. Remove baseplate assembly by removing bolts attaching baseplate to housing.
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52-14-21 Page 404 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Aug 15/79
C. Remove remainder of mechanism located inside housing as follows:
(1)
Remove bolt, washer and spacer (13) (located on outside of housing) from spindle (12), and remove spindle. Remove spacer from underneath housing.
NOTE: The spindle (12) may be difficult to pull out of bushings in crank assembly (11).
(2)
Working from outside of housing, remove cotter pin (2, figure 401) and washer (3) from spindle (4) and remove spindle by pulling out through opposite side of housing with cam follower (l), adjustment plate (5), and splined eccentric (8) still attached.
CAUTION: AVOID DAMAGE TO LINING OF SELF-LUBRICATED BEARING IN CRANK ASSEMBLY (6).
(3)
Remove linkage consisting of lockout crank assembly (6), link (9), crank assembly (11), torsion springs (18, if installed) and (19), link (29) as a unit by lowering through bottom of housing.
(4)
Check for loose fit bushings on either side of the housing at the two spindle shaft installation positions. If bushings are loose fit, save and identify for installation.
5. Install Aft Airstair Drive Emergency Extension Latch and Lockout Mechanism
A. If used parts are being installed, check for allowable wear (Ref 52-14-21).
B. Check mechanism housing for loose fit bushings at the two spindle shaft locations. Install bushings as required and maintain in installed position for shaft installations.
CC.
Assemble and install linkage consisting of lockout crank assembly (6), link (9), crank assembly (11), torsion springs (18 and 19), and link (29) to allow insertion in housing as a single unit.
(1)
Assemble lockout crank assembly to link (9) with bolt, nut, and washer (7).
(2)
Attach link (9) to crank (11) with bolt, nut, and washer (10). Attach link (29) to crank (11) with bolt (20), nut, and washer through bearing and install fasteners with corrosion preventive compound and tighten nut to 50-70 pound-inches.
CAUTION: AVOID DAMAGE TO BUSHINGS AND TEFLON SURFACE OF BEARINGS IN CRANK ASSEMBLY.
(3)
Position assembled linkage in housing with lockout crank assembly up and with internally splined shaft on crank aligned with spindle shaft installation holes in housing.
D.
Install spindle (4) through housing and lockout crank assembly splined shaft (6). Secure with washer (3) and cotter pin (2).
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