UNCOMMANDED AUTOPLT ROLL.

Narrative

ON ARR INTO CLT; NC; WITH AUTOPLT ENGAGED IN 'A' CHANNEL; ACFT SUDDENLY SHUDDERED AND BEGAN A RAPID; UNCOMMANDED ROLL TO THE L. THE CAPT DISCONNECTED THE AUTOPLT AND ARRESTED ROLL USING NEARLY FULL R CTL WHEEL. ACFT WAS DSNDING THROUGH 12000 FT AT 250 KTS WITH AUTOPLT IN 'LNAV' AND 'LEVEL CHANGE.' FLT CONDITIONS WERE CLR AND SMOOTH. NEAREST ACFT WAS B737; 7 OR 8 MI AHEAD. REMAINDER OF FLT WAS NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE B737-300 FOR A UNITED STATES ACR. HE BELIEVES THAT THE AUTOPLT COMMANDED A ROLL BY THE SPOILER AS THERE WAS A SHUDDER SIMILAR TO RAISING THE SPOILERS WITH FLAPS EXTENDED. UNFORTUNATELY; THE RPTR DID NOT FOLLOW UP ON THE MAINT ACTION TAKEN TO CORRECT THE ACFT. THIS INCIDENT WAS WRITTEN UP IN THE LOGBOOK; AND THE ACFT WAS TAKEN OTS FOR SOME TIME. THE CREW WORKED WELL TOGETHER. THE RPTR REACHED FOR THE YOKE BUT BACKED OFF AS HE COULD SEE THAT THE CAPT WAS TAKING CTL FROM THE AUTOPLT. THE RPTR BELIEVES THAT THE CAPT WAS ON THE PHONE WITH THEIR ACR SEVERAL TIMES THROUGHOUT THE NEXT SEVERAL DAYS. THE RPTR HAD NEVER SEEN THE B737 ROLL AT THIS RATE. HAD THE CAPT NOT TAKEN THE ACFT QUICKLY; THE ACFT MIGHT HAVE GOTTEN INTO REAL TROUBLE. THE CAPT CALLED ARTCC REGARDING ANY OTHER TFC AHEAD THAT MIGHT HAVE CAUSED WAKE TURB IMMEDIATELY AFTER THE RECOVERY. THERE WAS NONE.