(1)  
Location Zone
 311 Area Aft of Pressure Bulkhead, LH
 312 Area Aft of Pressure Bulkhead, RH

 (2)  
Access Panel 312A Horizontal Stabilizer Jackscrew Access Door

 D.  
Procedure

 S 424-068
 (1)  
Install the limit switch assembly (Fig. 401):

 (a)  
Assemble the switch to the mounting bracket: 1) Install the switch (without the arm) to the mounting

 bracket. 2) Install the bracket-switch locknut. 3) Install the lockwire on the locknut. 4) Put the actuator arm on the switch shaft.
 CAUTION:_______DO NOT TIGHTEN THE ARM LOCKNUT. IF THE LOCKNUT IS TIGHT AND YOU TURN THE WORM SCREW, YOU CAN CAUSE DAMAGE TO THE LIMIT SWITCH.
 5)  Install the arm locknut.
 NOTE: Do not tighten the arm locknut.
____
 6)  Loosen the worm lockscrew.
 7)  With the switch in fully open (free) position, Adjust the adjustment worm screw: a) Use the feeler gage to measure the clearance of the
 actuator arm and the bracket tab.
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747-400 MAINTENANCE MANUAL
 b)  Make sure the clearance of the actuator arm and the bracket tab is 0.015 |0.005 inch
 (0.38 |0.13 millimeter).
 c) Tighten the lockscrew.

 CAUTION: DO NOT ADJUST THE SWITCH POSITION AGAIN AFTER YOU
_______ ADJUST THE WORM SCREW AND INSTALL A LOCKWIRE ON THE WORM LOCKSCREW. IF YOU ADJUST THE SWITCH, YOU WILL PUT IT OUT OF POSITION. THIS CAN CAUSE DAMAGE TO THE LIMIT SWITCH.
 8)  Install a lockwire on the worm lockscrew.
 (b)  
Install the switch assembly with the same bracket that was removed: 1) Install the switch assembly. 2) Install four screws, washers and nuts.

 (c)  
Install the switch assembly with a new mounting bracket: 1) Install the switch assembly. a) Install two screws in the slots of the mounting

 bracket.
 b) Install the nuts.

 NOTE: Do not tighten the nuts.
____
 2)  Move the switch assembly to a position where the clearance of the cam surface and the switch roller is in the limits shown in Fig. 401. a) Tighten the nuts in the slots of the mounting bracket.
 3)  Use the pilot holes in the structure to drill the mounting holes in the bracket. a) Install two screws, washers and nuts in the mounting
 holes.
 b) Tighten the nuts.

 S 434-201
 (2)  
Make a splice of the switch leads to the wire bundle (WDM 27-41-11, WDM 27-41-21).

 (3)  
Do this task: "Supply Electrical Power" (AMM 24-22-00/201).

 S 864-012
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 S 864-013
 (4)  
Remove the DO-NOT-CLOSE tags and close these circuit breakers:

 (a)  
P7, Overhead Circuit Breaker Panel
 1) 7E6, STAB TRIM L CONT
 2) 7E7, STAB TRIM L S/O VALVE
 3) 7E8, STAB TRIM L RATE
 4) 7C10, FLT CONT ELEC 2L AC
 5) 7C11, FLT CONT ELEC 2L DC
 6) 7C12, FLT CONT ELEC 1L AC
 7) 7C12, FLT CONT ELEC 1L DC
 8) 7E19, STAB TRIM R CONT
 9) 7E20, STAB TRIM R S/O VALVE
 10) 7E21, STAB TRIM R RATE
 11) 7C14, FLT CONT ELEC 1R AC
 12) 7C15, FLT CONT ELEC 1R DC
 13) 7C16, FLT CONT ELEC 2R AC
 14) 7C17, FLT CONT ELEC 2R DC

 S 864-014
 WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF ALL CONTROL
_______ SURFACES BEFORE YOU SUPPLY HYDRAULIC POWER. AILERONS, RUDDERS, ELEVATORS, FLAPS, SPOILERS, LANDING GEAR, AND THRUST REVERSERS CAN MOVE QUICKLY WHEN YOU SUPPLY HYDRAULIC POWER. THIS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
 (5)  Do this task to pressurize the hydraulic systems No. 2 and 3: "Supply Hydraulic Power" (AMM 29-11-00/201).
　
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