AFCS Compass Interface Diagram (WA N236WA-N259WA) 505
22-11-01 Figure 6 (Sheet 2) Jun 20/86
Page 16
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
505 AFCS VOR/ILS Navigation Interface Diagram
Jun 20/86 Figure 6A 22-11-01
Page 16A
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
B. Compass System Interface (Fig. 6)
(1)
Each compass system provides a heading reference from the compass coupler or RMI to the selected AFCS computer. The Captain's compass coupler or RMI is connected to AFCS computer A; F/O's compass coupler or RMI is connected to AFCS computer B. The compass outputs are also connected to the HSI and the mode control panel. The compass valid is derived from the DG and compass rack or from the compass coupler. This signal together with a power monitor provide the compass valid signal to the AFCS computer. The digital data bus interconnects the AFCS computer and mode control panel.
(2)
The mode control panel contains a dual differential synchro for preset heading with each compass system exciting a separate synchro which in turn provides an output to the HSI heading bug. Separate preset course differential synchros provide course pointer inputs for each HSI. Digital encoders in the mode control panel convert preset heading and preset course signals to digital data. This data is decoded in the flight control computer, compared to synchro data and provides mode control panel heading and course readouts.
(3)
Loss of compass valid disengages the autopilot. The autopilot cannot be re-engaged until a compass valid signal is present.
C. VOR/ILS Navigation Interface (Fig. 6A)
(1)
The GS deviation, VOR/LOC deviation, VL superflag and ILS 28 volt signals are hardwired from the VHF NAV units to the AFCS computers. No. 1 VHF NAV unit is connected to AFCS computer A and No. 2 VHF NAV unit is connected to AFCS computer B. The ILS 28 volts is provided for the ILS RLY (antenna transfer relay) and the relay ground is provided by APProach ground in the AFCS accy unit. The G/S superflag signal is interlocked thru contacts of the ILS RLY. This configuration permits vertical fin localizer antenna connection during takeoff and ensures switching to the nose radome localizer antenna during approach. ILS 28 volts is also cross connected to provide foreign flight director logic.
(2)
The VOR No. 1 course resolver for AFCS computer A is connected to the captain's mode control panel course resolver and selector; VOR No. 2 course resolver for AFCS computer B is connected to the first officers course resolver and selector. The VHF NAV system VOR and LOC/GS testing capability is inhibited whenever the applicable AFCS system is armed or engaged to VOR/ILS navigation signals.
505
22-11-01 Page 16B BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Oct 20/84
15. Operation
A. General
(1)
Analog and digital computation is used within the system. Digital circuits are used for cruise modes VOR, HDG SEL, ALT HOLD V/S etc., and all Flight Director modes while analog circuits are used for autopilot approach. The interfacing signals used for digital computation may be either digital (on the 429 data bus) or analog. All signals used for AP approach computation are received into the AFCS as analog signals.
(2)
ARINC 429 bus operation provides the digital interface for two-way communication between the FCC, DADC, PDC and the MCP. Each DADC is connected (hardwired) to a respective FCC and each FCC has a separate bus to the MCP. The MCP selects the bus (A or B) it will accept via logic analysis of the following equation: A Bus = A Valid . B 1st Up + B 1st Up . B Valid where UP=CWS + CMD. Also each FCC has a cross channel bus tie to the other FCC for cross talk to annunciators, mode selection, and counters. The A FCC (captain's) and B FCC (1st Officer's) utilize the cross channel tie as follows: Assume A FCC is up and valid. Thus the MCP selects the A bus. The data word for the captain's COURSE display is computed in the A FCC and the data word for the 1st Officer's COURSE display is computed in the B FCC. The B channel data travels via the cross channel tie and is relayed to the A FCC. The data for both displays is then sent on the A-bus to the MCP. For B-bus selection transfer of data would be transposed.
(3)
The MCP operational procedures or ground rules for response to the pushbutton and controls are as follows:
(a)
There will be no response to any of the MCP pushbuttons with both F/D switches OFF and both A/P ENGAGE paddles in OFF.
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