E.  Restore Airplane to Normal Configuration
(1)  
Disconnect pitot static source. Refer to Pitot Static System, Chapter 34.

(2)  
Replace access panel and remove air supply from pitot tubes.

(3)  
If no longer required, remove electrical power from the airplane.

500 
22-21-0 Page 506  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 15/70 

MACH TRIM ACTUATOR - REMOVAL/INSTALLATION
1. General
A.  The mach trim actuator is mounted on top of the elevator feel and centering unit (Fig. 401). If the actuator is replaced because of malfunction or to perform routine maintenance, the elevator does not have to be rerigged. However, if the elevator is being rerigged and the actuator is removed, personnel must ensure the actuator is extended and properly nulled out before it is reinstalled and the elevator rerigged. Ref Chapter 27, Elevator and Tab Control System.
2.  Equipment and Materials
A.  Rigging Pin E-5 - 0.309/0.311-inch diameter, 3.7 +0.25 inches long (MS20392-4)
NOTE:  Rigging pin is part of kit F70207-61 (preferred), F70207-3 (optional).
3.  Prepare for Removal
A.  Remove elevator systems A and B hydraulic power (Ref 27-31-0, MP).
B.  Open and safety tag mach trim circuit breakers.
C.  Remove tail cone access panel 3802 (Ref Chapter 12, Access Doors and Panels).
D.  Install rigging pin E-5 in aft control quadrant (Fig. 402).
4.  Remove Mach Trim Actuator (Fig. 401)
A.  Disconnect electrical connector from actuator.
B.  If installed, relieve tension on return springs. Unscrew eyebolt nuts on return springs each side of elevator feel and centering unit, but do not remove.
C.  Apply an upward pressure to the elevator surface or elevator feel and centering unit and remove double bolt, nuts and washers connecting actuator jackscrew to neutral shift crank.
NOTE:  Upward pressure required to rotate feel and centering unit may be relieved by moving control column aft until forward bolt can be easily removed.
D.  Remove two side mounting bolts retaining actuator and remove actuator.
5.  Install Mach Trim Actuator (Fig 401)
A.  Position actuator on top of elevator feel and centering unit and install two side mounting bolts, but do not tighten.
CAUTION:  ENSURE THAT ELEVATOR NEUTRAL SHIFT POSITION TRANSMITTER CRANK IS CORRECTLY ORIENTED IN THE UP DIRECTION.
NOTE:  The right side mounting bolt fits through two floating bearings on all installations. The left side mounting bolt may fit through a single bearing, a single bearing and a washer, or a double bearing. All bearings on the left side are sleeve retained in the centering unit. Refer to Details B and C of Fig 401 for positioning. Be sure the floating bearings and the washer (if used) are correctly positioned before installing the side mounting bolts. 
500 
Feb 20/86  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  22-21-11 Page 401 

G42426 H19520 H19525
Mach Trim Actuator Installation  500 
22-21-11 Page 402  Figure 401 (Sheet 1) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Aug 01/94 

500  Mach Trim Actuator Installation 
Nov 15/72  Figure 401 (Sheet 2) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  22-21-11 Page 403 

Rigging Pin E-5 Location  500 
22-21-11  Figure 402  Jun 20/85 
Page 404 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

B.  Apply an upward pressure to elevator surface or elevator feel and centering unit and install double bolt connecting actuator jackscrew to neutral shift crank.
NOTE:  Upward pressure required to rotate feel and centering unit may be relieved by moving control column aft until forward bolt can be easily removed.
If the Mach Trim Actuator does not satisfactorily align with the Neutral Shift Crank, adjust the Neutral Shift Crank per MM 27-31-91, R/I.
C.  Install washers and nuts on double bolt. Torque large nut to 85-100 pound-inches. Torque small nut to 30-35 pound-inches.
CAUTION:  TO AVOID DAMAGE, DO NOT RETORQUE LARGE NUT AFTER TORQUING SMALL NUT.
D.  Torque side mounting bolts to 20-25 pound-inches.
E.  If installed, torque eyebolt nuts to 30-40 pound-inches. Install cotter pins through each nut.
F.  Check neutral shift sensor crank alignment. Verify that crank is orientated in upward position (Fig 402).
G.  Connect electrical connector to actuator.
　
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