H29048
Elevator Neutral Shift Sensor Installation 500
22-11-121Page 402 Figure 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Jun 20/85
500 Position Sensor Indexing Marks (Astro)
Sep 20/82 Figure 403 22-11-121
Page 403
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
ELEVATOR NEUTRAL SHIFT SENSOR - ADJUSTMENT/TEST
EFFECTIVITY
GJ ALL EXCEPT B-2509 and B-2510
1. Elevator Neutral Shift Sensor Adjustment
A. General
(1)
The entire pitch channel of the autopilot system and all elevator rigging must be fully adjusted and operable before the following adjustment can be performed. The mach trim system must also be operable. Two breakout cables must be fabricated (Fig. 501).
(2)
Elevator neutral shift sensor voltage is proportional to the elevator position transducer voltage; therefore, the output from B system elevator position transducer must be determined and multiplied by 0.707 to determine the neutral shift sensor voltage. The following procedures determine the voltage and establish the null point voltage of the neutral shift sensor.
B. Equipment and Materials
(1)
VTVM - Hewlett Packard, Model 410C
(2)
Breakout cables (Fig. 501)
C. Prepare to Adjust Elevator Neutral Shift Sensor
(1)
Apply electrical power to the airplane and ensure load control center P6 is energized.
(2)
Depressurize hydraulic systems A and B (Ref 29-11-0, Maintenance Practices and 29-12-0, Maintenance Practices).
WARNING: PRESSURIZING HYDRAULIC SYSTEMS WILL SUPPLY POWER TO RUDDER, AILERON, ELEVATOR, SPOILER AND SPEED BRAKE SYSTEMS. CARE SHOULD BE TAKEN TO ISOLATE OR TAG SYSTEMS NOT BEING TESTED TO PREVENT INJURY TO PERSONNEL OR DAMAGE TO AIRPLANE AND EQUIPMENT.
(3)
Open pitch channel circuit breakers and ensure pitch axis is disengaged.
(4)
Ensure MACH TRIM circuit breakers are closed.
(5)
Ensure mach trim actuator is fully extended (Ref Chapter 27, Elevator and Tab Control System).
(6)
Remove tail cone access panel 3802 (Ref Chapter 12, Access Doors and Panel).
Oct 20/86 22-11-121 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
H29046
Breakout Cables 500
22-11-121Page 502 Figure 501 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Nov 15/68
(7) Set horizontal stabilizer at 0 degrees (3 units trim), equal to B dimension of 41.57 +0.05 inches (Ref Chapter 27, Horizontal Stabilizer Trim Control System).
D. Adjust Elevator Neutral Shift Sensor
(1)
Ensure the autopilot INTLK circuit breaker is closed.
(2)
Disconnect D-375 from right power control unit and connect breakout cable between D-375 and the power control unit.
(3)
Disconnect D-377 from neutral shift sensor and connect neutral shift sensor breakout cable between D-377 and neutral shift sensor.
(4)
Close the pitch channel circuit breakers.
(5)
Pressurize hydraulic system B (Ref 29-12-0).
WARNING: MAKE SURE ALL PERSONNEL AND OBSTRUCTIONS ARE CLEAR OF AILERON, ELEVATOR, OUTBOARD SPOILERS AND RUDDER SYSTEMS. SURFACES AND CONTROLS MAY MOVE ABRUPTLY WHEN HYDRAULIC POWER IS APPLIED.
(6)
Jiggle aft control quadrant to ensure that system is centered.
(7)
Connect VTVM to test points 11 and 12 and record voltage.
(8)
Determine neutral shift sensor voltage by multiplying answer obtained in step (7) by 0.707.
(9)
Connect VTVM to test points 4 and 5 on neutral shift sensor breakout cable.
(10)
Loosen two screws on neutral shift sensor clamp only enough to allow the sensor to be rotated in the support.
(11)
Rotate neutral shift sensor housing slowly in both directions until voltage is as calculated in step (8), + 0.3 volts.
NOTE: Index marks cannot be seen with crank installed. When facing sensor, sensor housing should be rotated clockwise approximately 7 degrees.
(12)
Tighten sensor clamp screws and nuts within torque range of 8 to 12 pound-inches.
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