STABILIZER TRIM LIMIT SWITCHES - REMOVAL/INSTALLATION
1. General
A. Four stabilizer trim limit switches are installed on brackets along the stabilizer jackscrew aft compartment bulkhead (Fig. 401). Refer to 31-26-0 for coverage of the stabilizer takeoff warning switches. The stabilizer electric actuator airplane nose down limit switch and takeoff warning airplane nose down switch are combined in one switch.
B. The stabilizer trim limit switches terminate up and down travel of the horizontal stabilizer leading edge at predetermined limits. The switches are actuated to terminate stabilizer up and down travel by a cam mounted on the stabilizer center section jackscrew attach fitting.
2. Equipment and Materials
A. Actuator Trammel Bar - F80055-1
3. Remove Stabilizer Trim Limit Switches
A. Open stabilizer trim access door 3701.
B. Open stabilizer trim control circuit breaker on P6, and, if required, aural warning system circuit breaker on P6.
C. Disconnect limit switch wires from airplane wiring at splice connection.
D. Remove locknut securing switch arm to switch and pull arm off end of shaft.
E. Remove lockwire from switch attachment nut and remove nut while supporting switch. Pull switch free from bracket.
4. Install Stabilizer Trim Limit Switches
A. Check that stabilizer trim control circuit breaker on panel P6 is open. If required, check that aural warning system circuit breaker on P6 is open.
B. Position switch at appropriate bracket with switch body on correct side of bracket depending on switch location as shown in Fig. 401 and insert shaft through mounting hole in bracket. Secure switch in position with hexnut. Lockwire hexnut to bracket.
NOTE: Lead-in wires on switch are to point down on installation as shown in Fig. 401.
523
Nov 15/76 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 27-41-101 Page 401
G10936 G11053 G11055
Stabilizer Trim Limit Switch Installation 500
27-41-101 Page 402 Figure 401 (Sheet 1) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 15/69
524 Stabilizer Trim Limit Switch Installation
Nov 15/76 Figure 401 (Sheet 2) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 27-41-101 Page 403
Stabilizer Trim Limit Switch Installation 500
27-41-101 Page 404 Figure 401 (Sheet 3) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 15/69
C. Orient switch lever arm to approximate position for installation as shown in Fig. 401 and place lever on shaft, engaging serrations. Tighten hexagon locking nut finger-tight making sure washer has been installed.
NOTE: Hexagon locking nut will be tightened after switch is adjusted.
D. Connect switch wires to airplane wiring at splice connection (Ref Wiring Diagram).
E. Close stabilizer trim control circuit breaker on P6, and , if required, aural warning system circuit breaker on P6.
F. Adjust and test switch installation per instructions in 27-41-101, Adjustment/Test.
502
Nov 15/76 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 27-41-101 Page 405
STABILIZER TRIM LIMIT SWITCHES - ADJUSTMENT/TEST
1. General
A. The stabilizer trim limit switches terminate up and down travel of the horizontal stabilizer leading edge at predetermined limits. The switches are actuated by a cam mounted on the horizontal stabilizer center section support structure near the jackscrew attach fitting. The cam moves with the stabilizer to actuate the switches thus terminating travel at the limits for either normal electric stabilizer operation or autopilot operation depending on which system is being used for stabilizer trim.
B. Adjustment of the switches is accomplished by loosening a hexagon locking nut, a lockscrew and turning a gear until roller lever is in desired position with cam in proper switch actuation position. The lockscrew is tightened to positively lock roller lever in position and lockwired in position. The hexagon nut is then tightened.
C. The stabilizer electric actuator airplane nose down limit switch and the takeoff warning airplane nose down switch are both included in the same switch (Fig. 501). Refer to 31-26-0 A/T for adjustment of the stabilizer takeoff warning airplane nose up switch and for test of stabilizer takeoff warning switches.
2. Equipment and Materials
A. Actuator Trammel Bar - F80055-1
3. Stabilizer Trim Limit Switches Adjustment (Fig. 501)
A. Adjust Stabilizer Trim Limit Switches
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