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 - Unpublished Work - See title page for details.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 
Attitude display malfunctioning but gyro flag not in view  Attitude indicator  Check vertical gyro(s). Check appropriate vertical gyro relay contacts  Replace defective component 
Attitude display out of tolerance with flag removed from view  Vertical gyro(s) not erecting properly  Perform adjustment test  Replace defective component 
Pitch trim adjustment (where provided) not effective but attitude display appears normal  Attitude indicator  Check attitude indicators  Replace defective indicator 

5C3 
34-22-0 Page 102  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/83 

ATTITUDE REFERENCE SYSTEM -ADJUSTMENT/TEST
EFFECTIVITY
GJ ALL EXCEPT B-2509 and B-2510
1. General
A.  The following procedures describe two methods for testing the attitude reference systems in the airplane. The first procedure is an operational test in which only onboard equipment is used. The second procedure is a system test using the tilt tables to check system tolerances.
B.  The system test should be made prior to or concurrent with the adjustment/test of autopilot, weather radar, flight director, and navigation warning systems. If these systems are to be tested, performing those portions of test that require use of tilt table will save setup time.
2.  Operational Test
A.  Prepare for Operational Test
(1)  
Remove mounting bolts from vertical gyros.

(2)  
Connect electrical power to airplane and close GND PWR switch on panel P5. Energize No. 1 and 2 electronics buses by closing ac and dc circuit breakers on panel P6 and placing master switches in ON position.

(3)  
Check that following circuit breakers are closed: VERT GYRO-2, F/O HORIZ (ALT), INST XFMR-2, and INV CONT on panel P6; VERT GYRO-1, CAPT'S HORIZ (ALT), INST XFMR-1, CAPT'S HORIZ, F/O's HORIZ, and INSTR TRANS on panel P18.

B.  Roll and Pitch Servo Test
(1)  
Place VERTICAL GYRO transfer switch in NORMAL position. Check that both ADI's indicate airplane roll and pitch attitude 1 minute after power is applied.
　
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