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Rudder Ratio Changer Installation

 -
Rudder Ratio Changer Repairs

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Ratio Changer Servo Removal

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Ratio Changer Servo Installation

 There are two RRC assemblies on the airplane, an upper RRC and a lower RRC. This procedure is applicable to the two RRC assemblies.
 TASK 27-21-12-002-059
 2.  Rudder Ratio Changer (RRC) Removal (Fig. 201)__________________________________
 A.  Special Tools and Equipment
 (1)
G12001-50, Rig Pin Kit

 B.  
References

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

 (2)
AMM 24-22-00/201, Manual Control

 (3)
AMM 32-50-00/201, Steering

 (4)
AIPC 27-21-12, Fig. 3

 (5)
AIPC 27-21-15, Fig. 2

 (6)
AIPC 27-21-16, Fig. 2

 (7)
AIPC 27-21-52, Fig. 1

 (8)
WDM 27-21-12

 C.  
Access

 (1)  
Location Zone 323 Vertical Fin, Front Spar to Rear Spar 324 Vertical Fin, Rear Spar to Trailing Edge 325 Lower Rudder 325 Upper Rudder

 (2)  
Access Panel 312A Horizontal Stabilizer Jackscrew Access Door 324DL Inspection Access Panel 324FL Centering and Feel Mechanism Access Panel 324UL Inspection Access Panel

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 ALL  ú ú 01 Page 201 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 D.  Prepare for the Removal
 S 862-001
 (1)  
Supply electrical power (AMM 24-22-00/201).

 S 862-045

 (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 862-004
 CAUTION: MAKE SURE YOU OPEN THE CIRCUIT BREAKERS FOR THE RUDDER RATIO
_______ CHANGER. IT IS POSSIBLE TO CAUSE DAMAGE TO THE CONTROL UNIT IF YOU DO NOT OPEN THESE CIRCUIT BREAKERS.
 (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
 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 012-005
 (4)  
Remove the access panels 324FL and 324DL to get access to the lower rudder ratio changer (RRC)(AMM 06-09-07/201).

 S 012-046

 (5)  
Remove the access panels 324FL and 324UL to get access to the upper RRC (Ref 06-09-07/201).

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 ALL  ú ú 01 Page 202 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 492-006
 (6)  
Install the rig pin R-4 in the feel, centering, and trim mechanism.

 E.
Remove the Rudder Ratio Changer

 S 022-008
 (1)
Remove the upper (9) or lower (16) rudder ratio changer (RRC).

 (a)  
On the lower RRC, Disconnect the electrical connector (41) DM258 from the ratio changer servo (22).

 (b)  
On the upper RRC, Disconnect the electrical connector (33) DM560 from the ratio changer servo (22).

 (c)  
Disconnect the bonding jumper from the ratio changer servo (22).

 (d)  
Disconnect the output control rod (7) from the summing lever for the power control module.

 (e)  
Disconnect the input control rod (8) from the input crank of the RRC.

 (f)  
Disconnect the wire bundle clamp (29) from the RRC.

 (g)  
For the upper RRC, Hold the RRC (9) and remove the bolts (25, 26, 34, and 35) that connect the ratio changer to the structure.
　
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