S 862-051
 (2)  
Find the switches for the FLT CONTROL HYD POWER on the Pilot's Overhead Maintenance Panel, P461.

 (a)  
Put the four TAIL switches in the NORM position.

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747-400 MAINTENANCE MANUAL
 S 832-015
 (3)  Adjust and do a test on the rudder ratio changer (AMM 27-21-12/501).
 TASK 27-21-12-022-050
 4.  Rudder Ratio Changer Repairs (Fig. 201)____________________________
 A.  General
 (1)  
Use this procedure to replace the shear pin for the rudder ratio changer (RRC).

 B.
Parts ~.............................................................................. | AMM | | AIPC | ................. ............................ | FIG | ITEM | NOMENCLATURE | SUBJECT | FIG | ITEM | ................................................................................ | 201 | 24 | Shear Pin | 27-21-12 | 03 | 115 | | | | | | | | 2......…........…...................................…...........….....…........1

 C.  
References

 (1)  
AMM 06-09-07/201, Fin and Rudder Access Doors and Panels

 (2)  
AMM 24-22-00/201, Manual Control

 (3)  
AMM 27-21-12/501, Rudder Ratio Changer

 D.  
Access

 (1)  
Location Zone 324 Vertical Fin, Rear Spar to Trailing Edge 325 Lower Rudder 326 Upper Rudder

 (2)  
Access Panel
 315A Access Door
 324DL Inspection Access Panel
 324UL Inspection Access Panel

 E.  
Repair the Rudder Ratio Changer

 (1)  
Install the rig pin, E-2, in the aft torque tube for the elevator.

 S 862-052

 (2)  
Find the switches for the FLT CONTROL HYD POWER on the Pilot's Overhead Maintenance Panel, P461.

 (a)  
Put the four TAIL switches in the SHUTOFF position.

 S 492-016
 S 862-018
 (3)  
Open these circuit breakers and attach DO-NOT-CLOSE tags:

 (a)  
P7, Overhead Circuit Breaker Panel

 1)  For the lower rudder ratio changer, a) 7B14, LWR RUD RATIO AC PWR b) 7B15, LWR RUD RATIO DC PWR
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747-400 MAINTENANCE MANUAL
 2)  For the upper rudder ratio changer,
 a) 7B12, UPR RUD RATIO AC PWR
 b) 7B13, UPR RUD RATIO DC PWR

 (b)  P180, DC Power Distribution Panel
 1) 180E7, ELEV/RUD VLV SYS 2
 2) 180E22, ELEV/RUD VLV SYS 4
 3) 180H8, ELEV/RUD VLV SYS 1
 4) 180H23, ELEV/RUD VLV SYS 3

 S 032-048
 CAUTION:_______BE CAREFUL WHEN YOU DRILL THE SHEAR PIN. THE DRILL CAN CAUSE DAMAGE TO THE BUSHINGS IN THE TRUNNION CRANK OR THE BEARINGS IN THE ROD END.
 (4)  
Drill the shear pin (24) to remove it from the trunnion crank.

 S 222-020

 (5)  
Examine the rod end and the trunnion crank for worn parts.

 S 352-021

 (6)  
Install a new shear pin (24):

 (a)  
Put the rod end in the crank.

 (b)  
Make sure the grease fitting points down.

 (c)  
Install the shear pin with the manufactured head on the outer end of the trunnion crank.

 (d)  
Put the washer on the small end of the shear pin.

 (e)  
Rivet the shear pin.

 S 352-022
 (7)  
Use a 0.062 +0.003/-0.000-inch diameter drill to repair the inspection hole in the shear pin.

 S 862-023

 (8)  
Remove the DO-NOT-CLOSE tags and close these circuit breakers:

 (a)  
P7, Overhead Circuit Breaker Panel

 1)  For the lower rudder ratio changer,
 a) 7B14, LWR RUD RATIO AC PWR
　
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