AN AIRBUS 300-600 ON CLBOUT DISPLAYED SMALL OSCILLATIONS IN RUDDER AND RUDDER PEDALS. YAW DAMPER ON OR OFF; AUTOPLT ON OR OFF. OSCILLATIONS STOPPED IN LEVEL OFF.

Narrative

DURING CLIMBOUT FROM ZZZ ACFT DISPLAYED YAW OSCILLATIONS THAT WERE VERY SMALL IN MAGNITUDE. OSCILLATIONS STOPPED NEAR OR AT LEVEL OFF. NO CHANGE WITH AUTOPLT ON OR OFF; YAW DAMPERS ON OR OFF. FLT TO ZZZ1 COMPLETED WITHOUT FURTHER INCIDENT. SUPPLEMENTAL INFO FROM ACN 536731: I WAS THE CAPT OF FLT ABCD; ZZZ TO ZZZ1 ACFT X. DURING CLB OUT OF 10000 FT; CO-PLT AND I NOTICED A YAWING MOTION OF THE ACFT; VERY SMALL IN MAGNITUDE; AS IF SOMEONE WAS PUSHING ON THE RUDDER PEDALS (L AND R; AND R AND L) BACK AND FORTH. WE TRIED TO IDENTIFY THE PROB BY LOOKING AT THE ECAM PAGE AND NOTICED SLIGHT RUDDER MOVEMENTS WITHOUT EITHER OF US PUSHING ON THE RUDDER PEDALS. WE THEN PROCEEDED TO TURN OFF THE YAW DAMPERS ONE AT A TIME; THEN BOTH. THE ACFT CONTINUED TO YAW BACK AND FORTH. WE ALSO TURNED OFF THE FLT DIRECTORS; BUT THE YAWING CONTINUED. WE THEN TURNED THE AUTOPLTS ON; BUT THE YAWING CONTINUED. WE DECIDED TO LEVEL OFF AT FL240. AS POWER WAS REDUCED; THE ACFT STOPPED YAWING AS WE LEVELED OFF. WE THEN DECIDED TO CONTINUE TO CLB UP TO CRUISE ALTITUDE. WHEN CLB POWER WAS REINSTATED AND CLB INITIATED; THE ACFT STARTED TO YAW BACK AND FORTH AGAIN IN SMALL RHYTHMIC OSCILLATIONS 1 TO 1.5 PER SEC; UNTIL WE LEVELED OFF AT A CRUISING ALTITUDE OF FL350. THE YAWING STOPPED AT CRUISE ALTITUDE. THERE WAS NO FURTHER YAWING OF THE ACFT IN CRUISE FLT OR DURING DSCNT TO LNDG. THE LNDG WAS NORMAL. UPON ARR INTO ZZZ1 I WROTE AN ENTRY IN THE ACFT LOG BOOK. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE OSCILLATIONS WERE OBSERVED IN THE RUDDER PEDALS IN CLB ONLY AND WAS NOT NOTICEABLE IN THE AFT CABIN. THE RPTR SAID WHEN LEVELING OFF THE OSCILLATIONS STOPPED. THE RPTR STATED THIS OSCILLATION HAS BEEN OBSERVED BY HIM BEFORE AND BELIEVES IT IS CAUSED BY A COMBINATION OF ACFT WT; CENTER OF GRAVITY AND CLB. THE RPTR SAID AFTER LEVEL OFF IN CRUISE AND UNTIL LNDG IN ZZZ1 NO OSCILLATIONS OCCURRED.