A300 AIRBUS FLT CREW EXPERIENCED UNCOMMANDED RUDDER MOVEMENT CAUSING THE ACFT TO YAW SHARPLY LEFT AND RIGHT IMMEDIATELY AFTER TKOF.

Narrative

AFTER DEPARTING RWY XXX AT ZZZ; WX WAS CLR; WIND 320/21 GUST 26; I STARTED A LEFT TURN AROUND 400 TO 500 FT AGL AT AROUND 700-800 FT WE WERE IN LIGHT TO MOD TURB WHEN A SHARP BUT NOT VIOLENT YAW TO THE LEFT THEN TO THE RIGHT AND THEN BACK TO THE LEFT OCCURRED. I WAS ON THE RUDDER PEDALS; BUT FELT NO MOVEMENT IN THEM. I SAID TO THE CAPT 'WHAT WAS THAT?' HE SAID; 'ARE YOU ON THE RUDDERS?' I SAID; 'MY FEET ARE NOW ON THE FLOOR.' THEN WE GOT A SECOND CYCLE OF RUDDER KICKS; LEFT THEN RIGHT. HE HAD PUT HIS TOES LIGHTLY ON THE PEDALS AND FELT NO MOVEMENT. AT THIS TIME WE WERE CLBING THROUGH 2000 FT AND WERE COMING OUT OF THE TURB WHEN WE HEARD ATC TRYING TO GET HOLD OF US. THEY GAVE US A TURN AND A CLB AND WE CONTINUED TO CLEAN UP THE ACFT WITH NO OTHER MOVEMENTS. AT NO TIME WERE THERE ANY LIGHTS; ECAM; PADDLE SWITCH INDICATIONS OF A PROB. THE WHOLE INCIDENT LASTED 4-5 SECS. ON CLB OUT WE CONTACTED ZZZ1 VIA COMMERCIAL RADIO AND THEY RECOMMENDED WE GO BACK TO ZZZ. WE DID NOT DECLARE AN EMER AND LANDED WITHOUT INCIDENT. UPON ARR AT THE GATE MAINT PULLED THE TAPE ON THE FLT DATA RECORDER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE FLT DATA RECORDER (FDR) WAS ANALYZED AFTER THE INCIDENT AND THAT THE FLT AUGMENTATION COMPUTERS (FAC) AND YAW DAMPER REQUIRED REPLACEMENT. THE ACFT WAS SUBSEQUENTLY FLT CHECKED OK. HOWEVER; AFTER FURTHER ANALYSIS OF THE FLT DATA TAPES BY COMPANY MAINT; IT WAS FOUND THAT THE RUDDER HAD 63 EVENTS OF UNCOMMANDED MOVEMENT. THE ACFT WAS GROUNDED FOR FURTHER DIAGNOSIS AND MAINT. THE RPTR HAS FLOWN THE ACFT RECENTLY AND INDICATED THERE WERE NO FURTHER PROBS.