K77848
Transfer Switching Circuits  541 
34-22-0  Figure 3  Feb 01/74 
Page 4 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

K82911
5C8 Attitude Reference System SchematicFeb 20/89 Figure 3 34-22-0 Page 5/6 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

D.  The switching contacts shown in Fig. 4 are a continuation of those shown in Fig. 3 and transfer signals in the system. With the transfer switch in NORMAL position, the captain's ADI is slaved to the No. 1 vertical gyro and the gyro warning flag is monitoring the slaving circuits and vertical gyro No. 1. With the transfer switch in BOTH ON -2 position, the captain's ADI is slaved to the first officer's ADI and the gyro warning flag is monitoring the slaving circuits, vertical gyro No. 2, and the first officer's warning circuits. The first officer's components operate the same as the captain's, but with vertical gyro No. 2 as the primary reference. It can be seen that proper selection of the transfer switch will provide attitude reference to both ADI's and both flight directors from either vertical gyro. The inverter interlock logic will disconnect the first officer's warning circuits when the inverter comes on with the transfer switch in BOTH ON -1 position. Disconnecting these circuits will prevent them from adding to the current drain of the battery under emergency power conditions.
E.  The transolvers in the ADI's have three windings: a three-coil stator; and two, one-coil rotors, wound 90 degrees apart on the same core. Normal operation of the servo loop will ensure that the rotor that feeds the servo-amplifier is always at or near a NULL. This signal is fed to a null sensing circuit in the flag amplifier where it is used as a reference from the servo loop circuit. In the absence of this signal, the flag amplifier will fail and the warning flag will appear. The flag amplifier receives this NULL from both pitch and roll servo circuits so that a malfunction in either servo loop will trigger the flag. 
5C8 
Feb 20/89  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-22-0 Page 7 

ATTITUDE REFERENCE SYSTEM - TROUBLE SHOOTING
EFFECTIVITY

GJ ALL EXCEPT B-2509 and B-2510
1.  General
A.  A prerequisite for accurately trouble shooting any system is a good knowledge of normal system operation. Refer to vertical gyro system description and operation for review when required.
B.  To maintain integrity of the vertical gyro system and other associated systems that can be affected when a component is changed, a complete functional test as specified in adjustment/test procedure is required.
C.  When a malfunction occurs in the vertical gyro system and cannot be quickly isolated by substitution of a known serviceable component(s), then a thorough check should be made to determine if correct power is present, at the connector to the component. [Refer to electronic wiring diagrams for pin number(s).]
CAUTION: OBSERVE CORRECT POLARITY TO AVOID DAMAGE TO TEST EQUIPMENT.
D.  If trouble persists after voltage check as in C above, then check all related connectors for security of connection.
2.  Trouble Shooting Chart
A.  The trouble shooting chart should be used as a guide to help analyze possible source and/or determine the order in which to make tests or substitutions.
5C8
Jun 20/85 34-22-0 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Attitude display malfunctioning and gyro flag in view  Vertical gyro inoperative, instrument amplifier failure, or attitude director indicator  Check that appropriate circuit breakers are closed. Check dc voltage output from instrument amplifiers (Refer to Wiring Schematic for terminals.) Check valid dc voltage output through vertical gyro interlock  Replace defective instrument amplifier or attitude director indicator. If trouble still exists, replace defective vertical gyro 
Gyro flag in view but attitude display normal  Malfunction of VG transfer switch and/or vertical gyro transfer relay  Check Attitude Director Indicator. Check for continuity between vertical gyro relay and vertical gyro transfer switch  Replace defective component  
Gyro flag does not appear when appropriate circuit breakers are opened  Sticking flag   Check attitude indicators  Replace defective indicator 
Sluggish attitude display movement  Attitude indicator or vertical gyro not functioning properly  Perform adjustment test  Replace or repair faulty components 
　
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