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XA 7) Push HOLD light to ON. Verify that no malfunction codes
XA are displayed.
XA
XA NOTE:____ If the INS is no longer required, restore airplane
XA to normal. (Refer to INS - Adjustment/Test.)
XA
D. INS under PMS Waypoint Control (On Airplanes with PMS)
(1) The INS is placed in the PMS waypoint control mode, when the INS is
turned on and two continuous valid control words are received from
the PMS. If required, the INS can then be placed in the INS
waypoint control mode, by commanding the mode at the PMS CDU.
However, the INS can be returned to PMS waypoint control by
commanding the mode at the PMS CDU (Ref 34-62).
(2) INS operating procedures while under PMS waypoint control differ
significantly from the operating procedures when the INS is under
INS waypoint control. The major operating differences are
summarized as follows:
NOTE: The operating differences apply only to the INS connected
____ directly to the PMS, and when PMS control of waypoints has been selected.
(a)
Present position can be loaded only at the INS CDU. When the INS is in the NAV mode, the INS will accept present position (updated) data from the PMS.
(b)
The INS updating annunciators (pilots panels) will operate, when the PMS is transmitting DME updated present position to the INS.
(c)
The FROM-TO display on the INS CDU is always blank except during INS lamp test.
(d)
Leg switch and ALERT discretes are issued by the INS only on command from the PMS.
(e)
Waypoint data can be loaded only at the PMS CDU.
(f)
The INS can process only nine waypoints (the FROM waypoint, the TO waypoint, and the next seven sequential waypoints) while the PMS can be loaded with 9 x 4 or 36 waypoints. A new set of nine waypoint coordinates are transmitted from the PMS to the INS each time a leg switch occurs.
(g)
During the NAV mode, triple INS mixing for a three INS installation can be commanded only from the PMS CDU.
NOTE: INS systems not connected to the PMS must have triple
____
mixing independently commanded.
(h) During the NAV MODE, manual and/or DME position updates can be eradicated only by commands from the PMS CDU.
NOTE: INS systems not connected to the PMS must use INS
____
procedures to eradicate position update.
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(i)
INS action and malfunction codes can be displayed on both the INS CDU and the PMS CDU; and can be cleared, if intermittent, by pressing TEST on either CDU.
(j)
The INS HSI interface test can be commanded, during ALIGN, by pressing TEST on either the PMS CDU or the INS CDU.
(k)
The INS lamp test can be commanded only by pressing TEST on the INS CDU.
(l)
Any INS receiving waypoint data directly from the PMS does not have to be in the REMOTE function (CDU REMOTE key illuminated), to receive waypoint data from the PMS. The REMOTE function is disabled when the INS is under PMS waypoint control.
NOTE: Any INS not connected to the PMS will not receive
____ waypoint data from a PMS connected INS, even if REMOTE key is illuminated.
(3) For the INS to operate independently of the PMS, all PMS circuit breakers should be open.
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INERTIAL NAVIGATION SYSTEM - DESCRIPTION AND OPERATION
______________________________________________________
1. General (Fig. 1)
_______
A. The inertial navigation system (INS) automatically determines the navigation and attitude data of the airplane to keep the airplane on a predetermined course. External information inputs to the INS include barometric altitude (which is not used) and true airspeed from the central air data computer (CADC) and on airplanes with PMS, present position update information from the PMS. The INS does not require these data inputs but without them it will operate with degraded performance. The navigation data is displayed on flight instruments, allowing the flight crew to fly the airplane to the INS reference. The data is also supplied to the autopilot systems (Chapter 22), allowing the airplane to be automatically flown along the computed course if the autopilot/flight director is operated in the INS NAV mode with either channel A or B engaged.
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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(105)
