Narrative:

Uncommanded yaw to the right with rudder displaced about 2-3 inches. Aircraft reached 10 degree bank and yawed 10 degrees to the right before autoplt, autothrottle and yaw damper were turned off. Aircraft was brought back to level flight hand flying. No further action was required. Landing normal. Callback conversation with reporter revealed the following information: the reporter did not follow up the maintenance action for the uncommanded rudder deflection. He stated the deflection was rapid and violent but centered when power was removed from the autoplt and yaw damper system. The aircraft was removed from service for maintenance. The reporter did not follow the aircraft through maintenance nor did he recall any other details.

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Original NASA ASRS Text

Title: A B737-400 HAD A RAPID AND VIOLENT R RUDDER DEFLECTION OF ABOUT 2-3 INCHES ON APCH TO LGA. THE RUDDER CTRED AFTER THE AUTOPLT AND YAW DAMPER WERE TURNED OFF.

Narrative: UNCOMMANDED YAW TO THE R WITH RUDDER DISPLACED ABOUT 2-3 INCHES. ACFT REACHED 10 DEG BANK AND YAWED 10 DEGS TO THE R BEFORE AUTOPLT, AUTOTHROTTLE AND YAW DAMPER WERE TURNED OFF. ACFT WAS BROUGHT BACK TO LEVEL FLT HAND FLYING. NO FURTHER ACTION WAS REQUIRED. LNDG NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR DID NOT FOLLOW UP THE MAINT ACTION FOR THE UNCOMMANDED RUDDER DEFLECTION. HE STATED THE DEFLECTION WAS RAPID AND VIOLENT BUT CTRED WHEN PWR WAS REMOVED FROM THE AUTOPLT AND YAW DAMPER SYS. THE ACFT WAS REMOVED FROM SVC FOR MAINT. THE RPTR DID NOT FOLLOW THE ACFT THROUGH MAINT NOR DID HE RECALL ANY OTHER DETAILS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.