ADVANCED LGT EXPERIENCES UNWANTED RUDDER INPUT AND SWERVES DURING ROLLOUT AFTER A CAT III AUTOLAND APCH AND LNDG.

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WE WERE CLRED FOR THE 'CIVET 4' PROFILE DSCNT AND PASSING 'ARNES' WERE CLRED FOR A RWY 25L ILS APCH. BECAUSE THE WX WAS SO NICE; I ELECTED TO DO A FULLY COUPLED AUTOLAND APCH. THE ACFT WAS ON GS AND GLIDEPATH AND ALL 3 AUTOPLTS ARMED FROM APPROX 8000 FT ON DOWN. AT 1500 FT RADAR ALT (SHORTLY AFTER) THE AUTOLAND STATUS DISPLAY INDICATED 'LAND 3' AND MAINTAINED 'LAND 3' THROUGHOUT THE APCH. THE 'FLARE' AND 'ROLLOUT' MODES ALSO ARMED. THE 'FLARE' MODE ENGAGED AT THE NORMAL ALT AND THE 'ROLLOUT' MODE DID LIKEWISE. UP TO THIS POINT; ALL AUTOLAND FUNCTIONS/INDICATIONS WERE NORMAL WITH THE ACFT (WIRED) ON GS AND GLIDEPATH. RIGHT AFTER MY COPLT ANNOUNCED 'ROLLOUT' ENGAGED; THE ACFT PROCEEDED TO GIVE AN (ESTIMATED) 5 DEG L WING DOWN CONDITION. WHILE NOT ALARMING; IT CONCERNED ME BECAUSE: 1) THE WIND WAS FROM 330/5 KTS; AND 2) DURING AN AUTOLAND; A WINGS LEVEL CONDITION IS SUPPOSED TO BE MAINTAINED. THE L MAIN TOUCHED DOWN FIRST WITH THE ACFT ABOUT 2-3 FT L OF BUT TRACKING CTRLINE. ALMOST IMMEDIATELY FOLLOWING L MAIN TOUCHDOWN; I GOT A STRONG R RUDDER INPUT. UP UNTIL THIS TIME I HAD FELT NO UNUSUAL RUDDER INPUTS AS I HAD BEEN LIGHTLY BACKING UP ALL CTLS THROUGHOUT THE APCH AND LNDG. THE RATE OF RUDDER INPUT WAS STRONG ENOUGH TO SWING THE NOSE ACROSS THE CTRLINE AND I RESPONDED BY IMMEDIATELY DISCONNECTING THE AUTOPLTS WITH THE YOKE DISCONNECT AND APPLYING L RUDDER. THE TOUCHDOWN AND ROLLOUT WERE FAIRLY NORMAL AND SAFE BUT COULD HAVE BEEN OF REAL CONCERN IN LOW MINIMUM CONDITIONS AND/OR WITH SLICK RWY CONDITIONS. DURING THE FLARE BOTH THROTTLES RETARDED NORMALLY AND EVENLY. I DID NOT HAVE THE AUTOBRAKES ARMED FOR THE LNDG. BOTH THE COPLT AND MYSELF DID NOT OBSERVE ANY TFC XING THE RWY OR TAXIING PARALLEL TO THE RWY (EITHER 25L OR 25R) DURING THE APCH. ONE LIGHT TWIN LANDED AHEAD OF (5 1/2 MI) OUR ACFT ON 25L BUT HAD CLRED BOTH RWYS SOMETIME BEFORE OUR LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR DESCRIBED THE 'STRONG' RUDDER INPUT AS SIMILAR TO THE INPUT YOU WOULD USE IF AN ENG FAILED ON TKOF. HE SAID MAINT INOP'D THE #1 AND #3 AUTOPLTS AS A RESULT OF THE INCIDENT BUT; WHILE TAXIING OUT FOR THEIR NEXT TKOF; THEY WERE TOLD TO RETURN TO THE GATE WHERE THE ACFT WAS 'IMPOUNDED' AND THE FLT DATA RECORDER WAS REMOVED FOR STUDY. THEY WERE GIVEN ANOTHER ACFT FOR THEIR TRIP CONTINUATION. HE WAS CRITICIZED FOR NOT ADVISING APCH CTL OF HIS INTENT TO CONDUCT A CAT III AUTOLAND APCH.