(b)  
The status of the INS can be identified by a series of align mode numbers which appear in the 5th digit of the right data display of the CDU when the data selector is set to DSTRK/STS. The align mode number is 9 during STBY. The number changes to 8 as the INS enters ALIGN and decreases toward 0 as successive stages of the alignment process are completed. The NAV mode can be entered any time after the align mode number reaches 5. During ATT, the INS computer and CDU are shutdown and consequently no mode number is displayed.

 (c)  
OFF

 1)  All input power and battery power is removed from INS circuits with the exception of synchro excitation, 5 vac panel lighting, low voltage detection and shutdown circuitry, and INS turn on circuitry.
 (d) Standby (STBY) 1) The characteristics of the standby mode vary, depending on whether the INS is being turned on or is being downmoded from NAV, ALIGN or ATT. a) If the INS is being turned on, the INS navigation unit is brought up to operating temperature by fast warmup heaters and the gyro wheels are brought up to speed. Also, the INS platform is aligned to the airplane axes, and all instrument warning lamps controlled by the INS indicate warning. b) If the INS is being downmoded from a higher mode, the INS platform retains its alignment with local horizontal, and all instrument flags controlled by the INS except the attitude and platform heading flags will indicate warning.
 2)  Present position and flight plan data may be loaded in the INS during STBY. The airplane may be moved while in STBY but must not be moved during ALIGN.
 (e)  Align (ALIGN)

 EFFECTIVITY

 AIRPLANES WITH DELCO INS  CONFIG 1  02 A Page 66  Dec 25/9034-41-00
 1)  The INS computer progresses through a series of submodes in ALIGN. The INS performs leveling to local vertical and gyro compass alignment. At the end of the gyrocompass alignment period, a "ready-to-navigate" indication is provided on the MSU. An automatic gyro-bias drift calibration will be performed if the INS is left in ALIGN.
 NOTE: The submodes in ALIGN are shown as align mode
____ numbers in the 5th digit of the CDU right-hand display.
 2)  Align Mode Number 8
 a)  During mode 8, the INS platform is aligned to local horizontal, and the INS battery is tested. Attitude warnings are removed at the beginning of mode 8, but all other instrument flags controlled by the INS continue to indicate warning. The INS spends a minimum of 51 seconds in mode 8.
 3)  Align Mode Numbers 7 and 6

 a)  The primary function of modes 7 and 6 is to establish a known relationship between the INS platform and true north. This function continues unchanged throughout both modes. Loading present position into the INS allows it to go from mode 7 to mode 6. In mode 6, the INS compares the latitude of the loaded present position with the latitude it has computed as part of the alignment process, and it uses the results of this comparison, together with other information, to update certain self-calibration data. Assuming present position is loaded and the INS is allowed to progress to mode 6 shortly after it enters mode 7, the total time spent in the two modes will not exceed approximately 8.5 minutes.
 4)  Align Mode Number 5

 a)  Entry into mode 5 indicates that an adequate alignment of the INS platform has been achieved. The navigate mode can now be entered by setting the mode selector to NAV. The READY NAV lamp on the MSU will light when mode 5 is entered.
 5)  Align Mode Numbers 4 thru 0

 a)  Modes 4 through 0 indicate continuing operation of the self-calibration process begun in modes 6 and 5. If the INS is left in ALIGN, the self-calibration data will continue to be refined and the mode number will decrease to 0 as a straight line time dependent function so that align mode number = 0 is reached 17 minutes after align mode = 5 has been initiated. Each step in the countdown (align mode =5, =4, =3, =2, =1) takes the same amount of time (approximately 3.4 minutes).
 (f) Navigate (NAV)

 EFFECTIVITY
 AIRPLANES WITH DELCO INS  CONFIG 1  02 A Page 67  Apr 25/8734-41-00
 1)  In the NAV mode, all navigation data is computed and available for display. All warning flags controlled by the INS disappear from view. Two types of operation are available in the NAV mode: Normal inertial operation and aided inertial operation. a) Normal Inertial Operation
 2)  Each INS operates independently and depends on its own inertial instruments for all position and velocity data. The present position computed by each INS can be updated manually when the airplane passes over a known position reference. If there are three INS on board, all operating in the NAV mode, each INS commanded to do triple INS mixing (operating mode number 4) will update its present position approximately to the mid latitude and mid longitude of the three systems. a) Aided Inertial Operation (AF 116-150, 152-199; LH 011-
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：747飛機維護手冊AMM CHAPTER 34 - NAVIGATION 第34章導航2(102)