757 MAINTENANCE MANUAL
 ALCS ELECTROHYDRAULIC SERVOVALVE AND SOLENOID VALVES -
______________________________________________________ MAINTENANCE PRACTICES
_____________________
 1.  General_______
 A.  Two Autopilot Lateral Control Servos (ALCSs) are in the left wing root and one is in the right wing root. Get access to the servos through the main landing gear wheel wells.
 TASK 22-13-04-002-001
 2.  Remove the ALCS Electrohydraulic Servovalve or Solenoid Valves (Fig. 201)______________________________________________________________
 A.  References
 (1)  
24-22-00/201, Electrical Power-Control

 (2)  
29-11-00/201, Pressurize/Depressurize Main Hydraulic System

 B.  Access
 (1)  
Location Zones
 732/742 Main Landing Gear Body Door

 (2)  
Access Panels
 732/742 Main Landing Gear Body Door

 C.  Prepare for Removal
 S 862-002
 (1)  
Supply electrical power (Ref 24-22-00).

 S 862-003

 (2)  
Remove pressure from the L, C, and R hydraulic systems (Ref 29-11-00).

 S 862-004

 (3)  
Set the two F/D switches on the MCP to OFF.

 S 862-013

 (4)  
Open these circuit breakers on the overhead circuit breaker panel, P11, and attach DO-NOT-CLOSE tags:

 (a)  
11E17, FLT CONT COMPUTER POWER LEFT

 (b)  
11E18, FLT CONT COMPUTER SERVO LEFT

 (c)  
11E20, FLIGHT CONT CMPTR PWR CENTER

 (d)  
11E21, FLIGHT CONT CMPTR SERVO CENTER

 (e)  
11E35, FLT CONT CMPTR PWR RIGHT

 (f)  
11E36, FLT CONT CMPTR SERVO RIGHT

 D.  Remove the Valve
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 22-13-04
 ALL  ú ú 01 Page 201 ú Mar 20/90
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757 MAINTENANCE MANUAL
 S 112-005
 CAUTION: DO NOT LET CONTAMINATION GET INTO THE AUTOPILOT LATERAL CONTROL
_______ SERVO AND VALVES. THE AUTOPILOT LATERAL CONTROL SERVO AND VALVES ARE VERY SENSITIVE ELECTROHYDRAULIC DEVICES. CONTAMINATION IN THE SYSTEM CAN CAUSE DAMAGE TO THE EQUIPMENT.
 (1)  
Carefully clean the external areas of the valve and around the valve mounting surface.

 S 032-006

 (2)  
Remove the lockwire.

 S 022-007

 (3)  
Remove the mounting screws, the valve with the O-ring, and the seal plate from the servo assembly.

 S 862-008

 (4)  
Cover the servo openings to make sure contamination does not get into the hydraulic electrical passages.

 TASK 22-13-04-402-009
 3.  Install the ALCS Electrohydraulic Servovalve and Solenoid Valves (Fig. 201)________________________________________________________________
 A. Consumable Materials
 (1)  D00148 Hydraulic Fluid - Fire Resistant, BMS
 3-11

 B. References
 (1)  
22-00-02/201, Autoflight BITE

 (2)  
24-22-00/201, Electrical Power-Control

 (3)  
29-11-00/201, Pressurize/Depressurize Main Hydraulic System

 C. Access
 (1)  Location Zones
 732/742 Main Landing Gear Body Door

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 22-13-04
 ALL  ú ú 01 Page 202 ú Mar 20/90
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757 MAINTENANCE MANUAL
SEE A
ELECTRICAL CONNECTOR
SEAL PLATE
O-RING
WASHER (4 EACH VALVE)
SOLENOID
VALVE NO. 2

SCREW (4 EACH VALVE)
HYDAULIC 
RETURN 
LINE 
HYDRAULIC 
PRESSURE 
LINE 
ELECTROHYDRAULIC  SOLENOID 
SERVO VALVE  VALVE NO. 1 
A 

ALCS Electrohydraulic Servo Valve and Solenoid Valves
　
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