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 - Unpublished Work - See title page for details.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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