(b)
Each CDU consists of an alphanumeric keypad, mode and function select keys, and a display screen with 12 line select keys to choose items from menus displayed on the screen.
(c)
The left and right CDUs are located on the forward electronic control panel (P9) and the center CDU is located on the aft electronic control panel (P8).
F. Central Maintenance Computer System (CMCS)
(1) The component of the CMCS that interface with the weather radar are the left and right central maintenance computers (CMC's).
(a) The CMC sends a ground test command to the operating R/T to initiate a weather radar system ground test. The test command originates in the CDU and is sent through the CMC to the weather radar R/T. Test results are monitored and stored by the CMC's for display on the CDUs.
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(b)
The R/T BITE module continuously provides status data to the CMCs. The CMCs record and transmit this data to the CDUs for display.
(c)
The CDUs can request past flight data from the R/T BITE module memory for display.
G. Airplanes with operational PWS receives data or sends data to these airplane system(s).
(1)
Air Data System
(a)
The components of the air data system are the left and right air data computers.
(b)
The air data computers supply air speed, ground speed and drift angle to the WXR R/T with windshear capability.
(2)
Radio Altimeter System
(a)
The components of the radio altimeter system are the left and right radio altimeter receiver/transmitters.
(b)
The radio altimeters transmitter/receivers supply altitude above the ground data to the WXR R/T with windshear capability.
(c)
Radio altimeter data inputs are used to automatically activate the windshear mode of operation.
(3)
Enhanced Ground Proximity Warning System
(a)
The components of the ground proximity warning system are the GPW computer and four terrain display relays.
(b)
The GPW computer supplies an audio inhibit input to the WXR R/T.
(c)
The terrain display relays removes the weather radar data and adds terrain data from the ground proximity warning system to the navigation displays.
(d)
The GPW computer supplies the WXR R/T with antenna tilt angle data when the AUTO-tilt function is selected. The optimized tilt data is calculated from the altitude above the terrain and the terrain characteristics in the area. The resulting automatic tilt setting results in minimum ground clutter on the display while maintaining optimum weather detection capability.
(4)
Traffic Alert and Collision Avoidance System
(a)
The component of the traffic collision alert avoidance system (TCAS) is the traffic collision alert avoidance unit.
(b)
The TCAS unit accepts the PWS discrete inhibit output from the WXR R/T.
10. Operation
_________
A. General
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MAINTENANCE MANUAL
P7 OVHD CIRCUIT BREAKER PANEL
1
AIRPLANES WITH PWS ACTIVE
Weather Radar System Block Diagram Figure 2
L09476
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