B.
During airplane maneuvering the roll and pitch erection circuits are made inoperative in order to prevent slaving the gyro to a false vertical due to acceleration forces. The cutoff circuit is controlled by liquid level switches.
C.
Circuits in the vertical gyro monitor the following operational functions: pitch and roll autosyns, pitch and roll torquer current, gyro speed, erection system, and internal dc supplies. When all systems are operating properly the flag monitor provides 28 volts dc to external flag circuits.
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Jun 20/85 34-22-02 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
K77983
Attitude Reference System Component Location 505
34-22-02 Figure 1 Oct 20/84
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
3. Attitude Director Indicator (ADI)
A.
Each artificial horizon (contained in the ADI) consists of a moving tape assembly which displays the horizon line, pitch scale and roll index. The tape assembly is coupled to the rotors of the roll and pitch synchros and to the roll and pitch servomotors. When the servomotors turn, the synchros and the tape assembly are positioned simultaneously. Airplane attitude in roll is read from the roll index against the roll scale, and airplane attitude in pitch is read from the pitch scale against the miniature airplane symbol. A TEST switch at the lower left corner of the indicator provides a test of the servo circuits in the ADI. When the TEST switch is pressed, the attitude flag will come into view and the ADI will indicate 10 士 3 degrees pitchup and 20 士 4 degrees roll right from the prevailing airplane attitude at that time.
B.
An attitude warning flag is provided in each ADI to indicate loss of power, or malfunction of the gyro or of either servo-amplifier circuit in the system.
4. Operation
A. Both systems are made operational by closing the circuit breakers shown on the attitude reference system schematic (Fig. 2). After a brief period of time the gyros will erect and each ADI should indicate a level condition in both pitch and roll axis.
B. When the airplane is displaced in the roll plane, the gyro will transmit an ac signal which is not only related in amplitude to the degree of displacement, but also phase oriented to differentiate between left and right roll. The signal is passed to the roll servo-amplifier where it is amplified to drive the servomotor, which in turn drives the tape assembly. This ac signal is fed via the roll synchro on the roll motor shaft to ensure that the motor stops as soon as it has turned sufficiently to null out the error signal. Pitch displacement signals are handled in a similar way, and the electromechanical design is such that the tape assembly is able to respond to both pitch and roll signals simultaneously.
C. During turns, takeoffs and landings both pitch and roll circuits are made inoperative, to prevent slaving the gyro to a false vertical.
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Oct 20/84 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-22-02 Page 3
D. The operation of the transfer switch and relays is illustrated in the system schematic (Fig. 2). The schematic shows how the relay coils are connected with the dc supply through the relay contacts. The switch is shown in NORMAL position. When the transfer switch is set to CAPT ON AUX, the lower end of VG-1 latching relay coil is grounded; and since the other end of the coil is connected to +28 volts dc, it will latch over to the alternate set of contacts and remain there until energized once more. Note that the ground is removed from the coil when the relay switches contact position. In order to ground the coil once more and switch the relay back again, it will be necessary to return the switch to NORMAL. Switching to F/O ON AUX is carried out in a similar way. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 导航 NAVIGATION 1(79)
