(b)
Antenna tilt code messages on PWS airplanes.
1) The self-test also includes an antenna tilt code message for PWS airplanes to determine which external LRU is faulty. See Fig. 12. a) Messages with a minus sign are left system LRUs. b) Messages with a plus sign are right system LRUs.
2) In addition, visual and aural test messages occur on the flight deck instruments on PWS airplanes in a timed sequence. See Fig. 13.
3) Operation of the PWS automatic activation during a WXR test have these conditions. a) With the PWS active or if the airplane is in the air,
no flight deck effects are annunciated.
b) When the weather radar is in the TEST mode and a PWS alert is detected, the WXR system switches to the weather mode and shows WXR returns and the PWS ICONS are displayed on the NDs with the test message present.
c) When the PWS alert is no longer present, the map display returns are removed and the the WXR test pattern returns.
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(4)
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(c)
The sweep line is not present during self-test. Verification of a proper azimuth automatic boresight is accomplished by observing that the sweep line begins its motion from the dead-ahead position after the self-test mode is terminated.
(d)
If the test fails, the ND displays are described below and shown in Fig. 12: 1) The ND fault message WXR FAIL is displayed. 2) The ND LRU or fault condition is displayed. 3) The ND test pattern is displayed with ATT and WEAK faults. 4) The ND test pattern is removed for R/T, ANT and CONT
faults.Initiate the weather radar system self-test through the CMC using the left, right or center CDU as follows:
(a)
Press the MENU key. Use the line select key to choose <CMC from the menu.
(b)
Use the line select key to choose <GROUND TESTS from the CMC MENU.
(c)
Use the line select key to choose <34 NAVIGATION RADIOS from the GROUND TESTS SYSTEMS menu.
(d)
Use the line select key to choose <WXR-L or WXR-R from the GROUND TESTS MENU.
NOTE: If the system tests normal, the CDU displays PASS on the
____ same line as the system name. If the system fails the self-test, the CDU displays FAIL> on the same line. Use the line select key next to the fail message to see the reason for the failure on the GROUND TESTS MSG page.
System self test and fault analysis results are obtained by using the liquid crystal display (LCD) on the R/T front panel.
(a) The system monitoring circuits in the R/T check and compare selected voltages and signals during each program loop. If these checks or comparisions reveal any abnormality, the LCD memory stores the fault information. Two pushbuttons below the LCD control the sequence of software controlled buttons that result in different functions when pushed. These functions are used to isolate faults in the weather radar system or from inputs to the weather radar. These faults may be seen on the LCD after the R/T front panel TEST pushbutton is pushed.
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(b)
When the LCD TEST pushbutton is pushed a self test is performed the same as described above using the mode selector switch in the TEST position on the weather radar control panel.
(c)
The LCD operates with the TEST pushbutton as follows: 1) The default menu (or main menu) is shown below.
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