.
If problem persists, remove and replace
rudder power control unit.
.
If problem persists, replace yaw damper
coupler.
500
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Ground Test various faults not covered elsewhere
YD not msg. no. YD sw LATCHED: TYPE: Possible Causes:
engaged 22-21015 /wrg/YDC NO . Yaw damper engage switch not engaged during YDC BITE self test . Yaw damper coupler . Autopilot accessory unit Troubleshooting: . Perform the yaw damper coupler installation test, ref AMM12-12-01, page 401 step 4. . Verify resistance from D295 socket 14 to ground is less than 2.0 ohms with yaw damper engage switch in the OFF position. . Verify wiring between D295 socket 14, yaw damper engage switch, and autopilot accessory unit. . Inspect electrical connectors for bent or broken pins, contamination, or damage. . If problem persists, replace the yaw damper engage switch. . If problem persists, replace yaw damper coupler. . If problem persists, replace the autopilot accessory unit.
B hyd not msg. no. B hyd LATCHED: Possible Causes:
on 22-21016 /sensor NO . B system hydraulics not pressurized during YDC BITE servo test . Flight control system B pressure switch . Yaw damper coupler Troubleshooting: . Verify wiring between D295 socket 7 and D816 socket 3 at the flight control system B pressure switch. . Verify connection to ground at D816 socket 2 at the flight control system B pressure switch. . Inspect electrical connectors for bent or broken pins, contamination, or damage. . If problem persists, replace flight control system B pressure switch. . If problem persists, replace yaw damper coupler.
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YD actr limit msg. no. 22-21017 YD actr LATCHED: NO Possible Causes: . Excessive yaw damper actuator travel . Rudder power control unit position transducer . Yaw damper coupler Troubleshooting: . Verify resistance between: D295 socket 46 and D295 socket 47 is 80 ohms D295 socket 9 and D295 socket 1 is 100 ohms . Verify wiring at the rudder power control unit position transducer: D295 socket 46 and D295 socket 11 D295 socket 47 and D291 socket 12 D295 socket 9 and D291 socket 10 . Verify connection to ground at: D295 socket 1 D291 socket 9 at the rudder power control unit position transducer . Inspect electrical connectors for bent or broken pins, contamination, or damage. . If problem persists, replace rudder power control unit. . If problem persists, replace yaw damper coupler.
YD actr rigging msg. no. 22-21018 YD actr /rigging LATCHED: NO Possible Causes: . Asymmetric yaw damper actuator travel . Rudder power control unit position transducer . Yaw damper coupler Troubleshooting: . Verify resistance between: D295 socket 46 and D295 socket 47 is 80 ohms. D295 socket 9 and D295 socket 1 is 100 ohms . Verify wiring between at the rudder power control unit position transducer: D295 socket 46 and D295 socket 11 D295 socket 47 and D291 socket 12 D295 socket 9 and D291 socket 10 . Verify connection to ground: D295 socket 1 D291 socket 9 at the rudder power control unit position transducer . Inspect electrical connectors for bent or broken pins, contamination, or damage. . If problem persists, replace rudder power control unit. . If problem persists, replace yaw damper coupler.
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YDC, PCU incompat msg. no. 22-21019 YD actr LATCHED: NO Possible Causes: . Aircraft wiring . Restricted yaw damper actuator travel
. Rudder power control position transducer
. Yaw damper coupler
Troubleshooting:
. Inspect D295 socket 17, D295 socket 53, and YDC electrical connector for bent or
broken pins, contamination, or damage.
. Verify D295 socket 17 and D295 socket 53 resistance to ground is consistent with aircraft wiring diagrams, summarized;
737 MODEL D295 - 53 D295 - 17
-100/200/200 ADV RIDE QUALITY GROUND OPEN
-100/200/200 ADV OPEN OPEN
. Verify resistance between: D295 socket 46 and D295 socket 47 is 80
ohms
D295 socket 9 and D295 socket 1 is 100
ohms
. Verify wiring at the rudder power control unit transducer:
D295 socket 46 and D291 socket 11
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