Flight Director System Block Diagram  5A8 
34-26-0  Figure 2  Jan 20/82 
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

D.  Signal and/or power failure in a system, including failure of the steering command display, along with similar types of failure in any one of the systems (VOR/ILS navigation, attitude reference, or compass systems) providing data, is monitored through a warning flag circuit in the computer, and a warning is then displayed by the CMPTR warning flag in the ADI.
2.  Attitude Director Indicator
A.  The attitude director indicator furnishes a pictorial display of airplane attitude in bank and pitch, along with the bank and pitch steering commands. The bank and pitch steering commands are superimposed over an artificial horizon on a moving tape. The horizon line displays the pitch attitude of the airplane, and is read relative to the miniature airplane symbol. The bank marker index, connected by gearing to the tape, is read against the bank scale to give airplane bank angle. The tape is positioned by the bank and pitch servos, controlled by the roll and pitch attitude signals fed from the vertical gyro.
B.  The steering command display consists of the two V-pointers that flank the miniature airplane symbol to form a spread "V." The two V-pointers are servo-positioned, and controlled by the bank and pitch steering command signals fed from the computer (Fig. 3). The airplane is maneuvered in response to the commands displayed by the pointers. When the pointers are aligned alongside the miniature airplane symbol, the real airplane will be in the correct attitude to intercept, or remain on the selected flight path. If OFF is selected on the mode selector, the pointers are biased out of view.
C.  The runway symbol (localizer deviation pointer) at the lower part of the ADI comes into view when the VOR/ILS navigation system is providing a valid localizer deviation signal. The symbol moves laterally to display localizer deviation, and from 200 feet to touchdown, vertically to display low range radio altitude (LRRA).
D.  The RUNWAY flag covers the localizer deviation pointer when the LOC receiver is not in use or in the event of failure of the LOC receiver or signal. The RUNWAY flag also monitors the LRRA system for valid operation from 200 feet to touchdown.
E.  A horizontal pointer at the right side of the ADI indicates airplane deviation from the center of the glide slope beam. Pointer deflection above the center reference mark indicates that the center of the glide slope beam is above the airplane. The glide slope pointer is biased out of sight when the VOR/ILS receiver is tuned to a VOR frequency.
F.  A warning flag marked GS covers the glide slope pointer and scale in the event of failure of GS receiver or signal. It is biased out of sight when the glide slope deviation signal is valid or when the VOR/ILS receiver is tuned to a VOR frequency.
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Feb 20/86  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-26-0 Page 5 

G.  The ATT warning flag monitors the bank and pitch attitude display. It is spring-loaded to become visible when the bank and/or pitch attitude channels are not operating properly, or when power is lost to the attitude reference system. It is energized out of sight when the attitude reference system is-operating correctly.
H.  The CMPTR warning flag monitors power to the computer, plus, the various input warning signals from the systems feeding signals to the computer in specific combinations, depending upon the mode of operation of the computer. This is described under Operation.
I.  The slip indicator, at the bottom center of the indicator, is a conventional aid with a weighted ball in a liquid filled tube. It enables the pilot to monitor airplane slip, or skid in turns.
J.  A test button permits testing the integrity of the roll and pitch servo loops. Pressing the switch causes the pitch and roll indications to display an additional 10 degrees pitch up and 20 degrees roll right. The ATT flag should be visible while button is depressed.
K.  The speed command pointer and flag on the left side of the ADI are biased out of view by 28 volts dc supplied through the associated flight director dc circuit breaker.
3.  Horizontal Situation Indicator
A.  The horizontal situation indicator presents a plan view of the navigation situation. The display includes airplane heading with reference to magnetic north; the selected heading, the selected course and the distance to selected VOR/DME stations.
B.  Magnetic heading of the airplane is displayed by the compass card which is read with respect to the lubber line. When on magnetic heading, the card is positioned through the heading servo, and controlled by the heading signal fed from the compass system. This heading signal is also fed to the stators of the heading and course select synchros in the flight director control panel.
　
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