B737-300 RPTS UNCOMMANDED ROLL AFTER SELECTING FLAPS 40 DEGS ON APCH.

Narrative

UNCOMMANDED ROLL DURING ILS BEGINNING AT 1200 FT MSL AFTER SELECTING FLAPS 40 DEGS. ACFT ON AUTOPLT BEGAN TO OSCILLATE L TO R; AS IF BAD LOC SIGNAL. CLICKED OFF AUTOPLT AND AUTOTHROTTLE. STILL WANTED TO TURN L; AND HAD TO CONTINUOUSLY TILL TOUCHDOWN; 'KEEP CORRECTING COURSE.' FOLLOWED IMMEDIATE ACTION ITEMS FOR UNCOMMANDED ROLL -- AUTOPLT OFF; AUTOTHROTTLE OFF; YAW DAMPERS OFF. NO SPLIT FLAPS; THROTTLES OR APPARENT SPOILER DEPLOYMENT. LNDG SUCCESSFUL. +10 VREF AT TOUCHDOWN! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE RUDDER TRIM WAS REPEATEDLY CHKED BEFORE AND AFTER THE UNCOMMANDED ROLL AND THAT EVEN AFTER THE AUTOPLT WAS DISCONNECTED; THE ACFT CONTINUED TO ROLL L WHENEVER MANUAL CTL PRESSURE WAS LESSENED. HE STATED THAT THE ACFT WAS IMMEDIATELY GNDED AND INSPECTED FOLLOWING THE INCIDENT. THE ACR MAINT FACILITY DETERMINED THAT A WORN FLAP TRACK FAIRING PREVENTED THE FLAPS ON 1 SIDE ONLY FROM MOVING TO THE FULL 40 DEG POS. THE RPTR STATED THAT THE FLAPS INDICATED FULL 40 DEGS ON BOTH SIDES AT THE TIME OF THE INCIDENT AND THAT THE FLC WAS FATIGUED AS THIS WAS THE FINAL LEG OF A LONG AND TRYING DAY. THE ACR AND RPTR MADE APPROPRIATE COMPANY IRREGULARITY AND FAA RPTS CONCERNING THE INCIDENT.