34-41-00
R304 B556 R288 R306 R302 R297
P73 FLIGHT INSTRUMENT SWITCHING RELAY PANEL R449
R855 B231 R856
R450 R288 FLIGHT DIRECTOR COMPUTER SELECT
RELAY NO. 1 (CAPT)
R298 R289 FLIGHT DIRECTOR COMPUTER SELECT
RELAY NO. 2 (F/O)
R303 R297 RADIO/INS RELAY NO. 1 (CAPT)
R298 RADIO/INS RELAY NO. 2 (F/O)
R307 R302 INS TRANSFER RELAY NO. 1 (CAPT)
R289 R303 INS TRANSFER RELAY NO. 2 (F/O)
B557 R304 ATTITUDE TRANSFER RELAY NO. 1 (CAPT)
R305 R305 ATTITUDE TRANSFER RELAY NO. 2 (F/O)
R306 COMPASS TRANSFER RELAY NO. 1 (CAPT)
R307 COMPASS TRANSFER RELAY NO. 2 (F/O)
R449 VOR/ILS TRANSFER A RELAY NO. 1 (CAPT)
R450 VOR/ILS TRANSFER A RELAY NO. 2 (F/O)
R855 VOR/ILS TRANSFER B RELAY NO. 1 (CAPT)
R856 VOR/ILS TRANSFER B RELAY NO. 2 (F/O)
B231 INSTRUMENT SWITCHING ACCESSORY BOX
B556 VOR/ILS ISOLATION AMPLIFIERS
B557 VOR/ILS ISOLATION AMPLIFIERS
NOTE: WIRING AND CONNECTOR DETAIL
OMITTED FOR CLARITY.
Flight Instrument Switching Relay Panel
Figure 11
EFFECTIVITY
AIRPLANES WITH LTN-72RL OR CONFIG 3
LTN-92 INS799 Page 27
34-41-00
Apr 25/91
B. The captain's HSI receives INS navigation information from INS No. 1 or No. 3 and the first officer's HSI receives INS navigation information from INS No. 2 or No. 3 as selected from the INS transfer switch on the captain's flight instrument panel. An illuminated annunciator adjacent to the switch shows which two of the three INS systems are supplying information to the HSI's (Fig. 1).
C. The horizontal situation indicators, operating in a true heading-oriented INS mode, display airplane true heading, desired track, actual or ground track, drift angle, distance to the next waypoint, track angle error, and ground speed. BCD signals representing distance, ground speed, and drift angle are decoded in separate digital displays.
(1)
True heading is displayed by the azimuth card relative to the lubber line.
(2)
Track angle error is displayed by the angle between the course arrow and the drift angle bug.
(3)
Ground track information is displayed by the drift angle bug read against the azimuth card relative to the true north (000.).
(4)
Drift angle is displayed by the angle between the drift angle bug and the lubber line.
(5)
Crosstrack deviation is displayed by the course deviation bar relative to the course deviation scale.
(6)
Desired track information is displayed by the course arrow read against the azimuth card.
D. Two separate digital readouts are provided in each HSI, one in each of the upper corners of the insturment bezel. The left-hand readout normally displays distance to the next waypoint indicated in the TO display of the CDU. The right-hand digital readout displays ground speed information.
E. The HSI provides annunciators to indicate operating status.
(1)
A meter-operated VOR-ILS flag appears in the upper left area of indicator when a radio or magnetic system is being used as the source of navigation information. In the INS mode of operation the VOR-ILS flag retracts to reveal an INS legend.
(2)
A data source annunciator is located below the VOR-ILS/INS annunciator. The data source annunciator displays the numbers 1, 2, or 3 which correspond to the system in use.
(3)
A heading information annunciator is located behind the lubber line at the top of the indicator. A meter-operated MAG flag appears when magnetic heading is displayed on the HSI azimuth card. When true heading is displayed the MAG flag retracts to reveal a TRUE legend which signifies a true heading-oriented display.
(4)
An ALERT annunciator is located in the left portion of the instrument face. When the INS signifies that the airplane is within 2 minutes of its selected waypoint or destination, the ALERT annunciator illuminates.
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