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ELECTRONIC CIRCUIT BREAKER PANEL P7
ESSENTIAL FLIGHT INSTRUMENT BUS
PWR - INS 1 PWR - INS 1 CAPT FLT INST SW RELAYS; -ATT/COMP STAB AND -INS INS ADS EXCIT 1
FLIGHT INSTRUMENT BUS NO. 2
PWR - INS 2 PWR - INS 2 PLATF HDG INS 3 F/O FLT INST SW RELAYS; -VOR/ILS INS, -ATT/COMP STAB AND -INS ATT INS 2 ATT ADI 2 INS ADS EXCIT 2 PLATF HDG INS 2 NAV INS 2 HSI 2
STANDBY BUS
ATT INS 1
ATT ADI 1
HSI 1
PLATF HDG INS 1
ALT PLATF HDG INS 3
CAPT FLT INST SW RELAYS -VOR/ILS INS
NAV INS 1
OVERHEAD CIRCUIT BREAKER PANEL P126
FAIL OP BUS
PWR - INS 3
PWR - INS 3
ATT INS 3
ALT ADI 1
ALT ADI 2
NAV INS 3
ALT HSI 1
ALT HSI 2
XFMR 8
XFMR 9
INS Circuit Breakers
Figure 19
EFFECTIVITY
CONFIG 2AIRPLANES WITH LTN-72 INS
799 Page 49
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Apr 25/86
T34620
(b)
If the waypoint to be bypassed is not the next waypoint, the track change may take place at the next waypoint. For example, if the airplane is halfway to WPT 2 on track 1 2 when a descision is made to bypass WPT 3 and go directly to WPT 4 from WPT 2, initiate a track leg change at waypoint by entering track 2 4 on the data keyboard.
(c)
If one of the waypoints to be bypassed is the next waypoint, initiate a track leg change from present position.
(12)
Present-Position Checking and Updating
(a)
If a known position is to be overflown or an accurate position fix is available by other means, the INS present position can be checked by putting the display select switch in POS and then pushing the HOLD pushbutton as soon as the aircraft position is coincident with the fix position. The INS present position display will freeze, and it can then be compared with the fix position. If no updating is necessary the HOLD pushbutton should be depressed to restart the POS display. The INS will automatically compensate for any distance flown while the display was frozen.
(b)
If updating is desired it can be accomplished by loading the fix latitude and longitude in the same manner as loading present position data. If both latitude and longitude are updated, numerical displays will restart when the INSERT pushbutton is pressed. If only latitude or longitude is updated, pressing HOLD pushbutton will restart display. When the display restarts, the system will automatically compensate for any distance flown while the display was frozen, including the change due to updating.
(13)
System Malfunction and Warning System
(a)
The INS includes extensive self-testing and monitoring circuits. If any of these circuits detects a malfunction, the WARN light will illuminate indicating that navigation data are not reliable. Warning flags or lights on the flight director will also indicate the malfunction.
(b)
When primary power fails or is interrupted and the INS automatically transfers to backup dc power, the CDU BATT annunciator comes on and remains on until primary power is restored, the INS automatically transfers to primary power.
(c)
When backup power is less than the minimum required to operate the INS, the MSU BATT annunciator comes on.
(d)
During alignment status 70, the INS performs calculations that use the present position coordinates inserted at the start of the alignment. If the present position coordinates are incorrect, the results of the calculations are illogical and the INS generates a signal that causes the WARN annunciator to flash and holds the alignment in status 60.
EFFECTIVITY AIRPLANES WITH LTN-72 INS
CONFIG 01 A Page 50 Aug 25/87
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(e)
The INS monitors the elapsed time from the start of alignment and anticipates that the alignment status will count down to 02 or less and that the READY NAV annunciator will come on approximately 12 to 15 minutes after the mode selector switch is set to ALIGN. If these two conditions are not satisfied, the WARN annunciator flashes.
(f)
If a hard system failure occurs, the WARN annunciator comes on and, in certain types of hard failure that might cause damage to the INS and/or airplane, the INS shuts itself off and latches the INU fault indicator to a yellow condition. The fault indicator remains latched.
(14)
Attitude Reference Mode
(a) If the WARN light comes on, the mode control switch should be turned to the ATT REF (attitude reference) mode. In the attitude reference mode, the INS will provide pitch, roll, and platform heading information only, and the displays will extinguish. If the malfunction that caused the WARN light is in the attitude reference portion of the system, the WARN light will stay on and the mode selector switch should be turned to OFF. Once the system is taken out of NAV, it cannot be restored to the navigation mode while in flight and provide meaningful data. On the next INS turn-on, there may be an action and malfunction code displayed in DSR TK/STS. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航2(123)
