A321
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Other / Unknown
General None Reported / Taken
Aircraft; Procedure; Company Policy
While on approach with the flaps extended and autopilot engaged; both pilots felt the rudder pedals rapidly moving about an inch or two. The rudder pedal movement stopped when the autopilot was disengaged and did not reoccur. After entering the incident in the log book; I was contacted by a member of my union's safety committee who informed me that there have been approximately a dozen similar instances on this particular aircraft.
A321 Captain experienced rudder vibration in flight.