F. The HSI furnishes warning flags to annunciate heading and navigation failures.
(1) A HEADING flag drops into view behind the lubber line and obscures part of the azimuth card in event of loss of the heading valid signal from the input data source, loss of heading servo power, or excessive heading servo error signal.
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INS Cooling and Battery Warning
Figure 12
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(2) A meter-driven navigation failure warning flag is located adjacent to the course deviation bar. The flag appears when the navigation data is invalid.
G. The HSI biases the markers (bugs) out of the way when the information is invalid.
(1)
The preset heading bug is biased to the "6 o'clock" position when the HSI is displaying INS data.
(2)
The drift angle bug is biased out of view upon loss of INS navigation flag voltage.
15. Attitude Director Indicator (Fig. 10)
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A. Two attitude director indicators (ADI) are installed in the airplane, one on each pilot's instrument panel. The indicators are used primarily to display airplane attitude. Each is, however, a composite instrument which accepts and displays glide slope and localizer deviation, radio altitude, speed deviation, decision height, flight director commands, and rate of turn signals from other navigation systems.
B. The captain's ADI receives pitch and roll attitude information from INS No. 1 or 3 as selected from the ATT/COMP STAB switch on the captain's flight instrument panel. Similarly, the first officer's ADI receives attitude information from INS No. 2 or 3. An illuminated annunciator adjacent to the switch shows which two of the three INS systems are supplying information to the ADI's (Fig. 1).
C. Airplane attitude is indicated by a dc torque motor-driven sphere, representing the horizon and moving relative to a fixed airplane symbol near the center of the instrument face. The sphere rotates in pitch and roll to correspond to the airplane attitude. In the event of power loss to the indicator, loss of the attitude valid signal to the indicator or detection of failures by the indicator monitor circuits, the instrument attitude (ATT) warning flag appears to indicate an invalid attitude indication.
D. Each ADI contains self-test provisions. When the test button on the front of the indicator is depressed, the sphere will indicate a change in attitude indication of approximately 20 degrees right bank and 10 degrees climb. The attitude warning flag will also appear.
16. INS No. 3 Annunciator (Fig. 1)
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A. When the No. 3 inertial navigation unit provides a valid attitude flag signal, the INS-3 annunciator on the pilots center instrument panel displays black. The annunciator displays red when the attitude flag signal is not valid.
17. Flight Instrument Switching Relay Panel (Fig. 1 and 11)
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A. The horizontal situation indicators and attitude director indicators are multipurpose instruments used to display flight information from several different systems. Because of this, INS information is transferred to these instruments through flight instrument switching relays.
B. The various instrument switching relays are located on the flight instrument relay panel (P73) which is attached to the left side of the electronic equipment rack (E1) in the main equipment center.
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C. The portion of the switching network involving the INS consists of a captain's VOR-ILS/INS switch and transfer relay, a first officer's VOR-ILS/INS switch and transfer relay, captain's and first officer's INS transfer relays, captain's and first officer's attitude/compass stabilization transfer relays and a flight instrument switching accessory box. The INS and attitude/compass stabilization transfer relays are controlled by the INS and ATT/COMP STAB switches on the captain's flight instrument panel. There are no attitude and INS transfer switches on the first officer's flight instrument panel.
(1)
The captains VOR-ILS/INS switch controls the captain's VOR-ILS/INS transfer relay which allows the captain's HSI to display heading information from either the radio navigation and magnetic heading reference systems, or the INS. The first officer's VOR-ILS/INS switch and transfer relay function in a similar manner for the first officer's HSI.
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本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航2(135)
