AF 121, 122; SN 351-399 CONFIG 3 01 B Page 106 Sep 25/9434-43-00
WEATHER RADAR SYSTEM - TROUBLE SHOOTING
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1. General
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A. The trouble shooting procedure is based on the performance of the weather radar system fault isolation circuits. These circuits continuously monitor system operation in all modes.
B. The circuits identify most system malfuncitons, and display alphanumeric messages (in message slots on the display unit) as an aid to trouble shooting system failures.
C. AF 160, 162-171; The message slot locations (Fig. 101) and the message(s) displayed are described as follows:
(1)
Message slot 1 - Located at top left corner, presents selected mode of operation. These will be displayed as WX, WX+T, TURB, MAP, GCS or TEST.
(2)
Message slot 2 - Located at top center of display, annunciates alert or fault messages of HOLD, WEAK or FAIL. The HOLD message will flash 1 second on and 1 second off in yellow characters when the HOLD message is selected on indicator. FAIL will flash whenever system failure is detected. WEAK will flash when system detects a loss of calibration, such as transmitted power, or receiver sensitivity has fallen below desired level but system is still usable. A target alert message of WX+T will alternate with HOLD should turbulent weather be detected while in the WX+T or TURB modes of operation. If the data bus input to the indicator is not detected, a flashing blue (cyan) colored FAIL message will be present.
(3)
Message slot 3 - Located at top right. Displays selected range in blue color.
(4)
Message slot 4 - Located directly below message slot 1 (selected mode), will normally present a set of green, yellow, and red color bars. If display experiences a color scheme failure, message slot will identify modified color scheme.
(5)
Message slot 5 - Located directly below message slot 3 (selected range). Displays range mark interval (in nautical miles) for selected range.
(6)
Message slots 6, 7, 8, 9 - Located directly below message slot 4 (color bars). Displays system detected unit faults. Should system failure occur (FAIL in message slot 2) the LRU causing failure will be displayed as T/R (receiver-transmitter), ANT (antenna), CTL (control panel), or DSP (indicator). The faults are priority rated with the highest priority displayed in slot 6 with descending priority in slots 7, 8 and 9. If the data bus input to the indicator is not detected, combined FAIL and T/R blue (cyan) messages in slots 2 and 6 respectively will be displayed. All other fault messages are in yellow.
(7)
Message slot 10 - Located at the bottom left corner, displays system gain setting. One of following set of characters will be displayed: MAX, -01, -02, -03, -04, -05, -06, -07, -08, MIN. Each gain step reduces system sensitivity by 2db.
EFFECTIVITY
AF 160, 162-171, 183, 184 CONFIG 4 01 Page 101 Sep 25/9434-43-00
(8)
Message slot 11 - Located at bottom left of indicator displays IDNT when ground clutter suppression is selected. Otherwise this slot is blank.
(9)
Message slot 12 - Located bottom center of display message slot 12 displays system selected. This slot will be blank when system 1 is selected and will display S2 when system 2 is selected.
(10)
Message slot 13 - Located at bottom right center, displays system stabilization status. For stabilized operation, INS providing proper inputs, this slot will be blank. A flashing ATT will be displayed when an attitude input failure is detected (INS OFF or providing invalid pitch or roll signals). SAT will be displayed when system stabilization limits are exceeded due to unusual attitude maneuvers. All messages are blue color.
(11)
Message slot 14 - Located in bottom right corner, displays selected antenna tilt position. Message characters are +15.00 to -15.00 in
0.25 increments. Should antenna tilt be different than selected tilt, antenna failure message will be displayed (a yellow flashing FAIL in message slot 2 and an ANT message in slot 6).
D. AF 183, 184; The message slot locations (Fig. 101) and the message(s) displayed are described as follows:
(1)
Message slot 1 - Mode messages located at top left corner, presents selected mode of operation. The messages are WX, WX+T SCH, MAP or TEST.
(2)
Message slot 2 - The alert and fault messages located at top center of display, annunciates flashing messages of WEAK or FAIL. FAIL will flash whenever a system failure is detected. WEAK will flash when system detects a loss of calibration, such as transmitted power, or receiver sensitivity has fallen below desired level but system is still usable.
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