A319
Flight Crew Air Transport Pilot (ATP)
Distraction; Troubleshooting
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury
Aircraft Equipment Problem Dissipated; General Maintenance Action
Aircraft
Descending through FL240 at 320 KTS. On autopilot; we experienced rudder movement (back and forth wagging) with no input from the flight crew. It was significant enough to hear a thumping noise on the flight deck and enough movement to cause a flight attendant in the rear of the aircraft to fall against the wall/bulkhead. I disconnected the autopilot and hand flew the aircraft slowing it down to 270 KTS but the wagging continued intermittently.  I reconnected the autopilot at the slower speed and again could tell the aircraft seemed to be getting some cross control inputs but was flying the commanded course and profile.  Because all seemed under control although out of trim; we continued to a normal landing at our filed destination and contacted company Dispatch and Maintenance at the gate.I have no idea what caused this uncommanded rudder movement. We received no ECAM malfunction indications in flight and post flight maintenance reports indicated all normal.
The reporter stated that one of his thoughts during the early stages of this event was the B737 Pittsburgh uncommanded rudder movement accident and so he disconnected all automation to determine his level of control. Aircraft control was not diminished; however the rudder movements continued intermittently with the autopilot OFF until the aircraft was fully configured for landing. A maintenance log write up was made and Maintenance later reported that a 'control unit' was replaced. The exact 'control unit' component was not divulged.
An A319 developed an uncommanded rudder movement during descent through FL240 at 320 knots significant enough to be heard in the cockpit and cause an aft galley flight attendant imbalance. No ECAM alerts coincident with the event.