What was found
WITH AUTOPILOT ENGAGED AND NAVIGATING DIRECTLY TO FMG VOR, AND DESCENDING AT APROXIMATELY 1700 FT PER MINUTE, A MOMENTARY AILERON MISTRIM MESSAGE APPEARED AND THE AIRPLANE BEGAN TO GO INTO A 15-20 DEGREE RT BANK AND PROCEED OFF COURSE. AFTER DISCONECTING THE AUTOPILOT THE AIRPLANE RESISTED MANUAL ROLL CONTROL FROM ME FOR ABOUT 1-2 SECONDS AND THEN ROLL CONTROL BECAME NORMAL AND THE AIRPLANE FLEW NORMALLY HAND-FLOWN. THE FMS COMMAND BARS GAVE PROPER COMMANDS TO CORRECT COURSE DURING THIS EVENT WHICH LASTED 5-8 SECONDS. LANDING UNEVENTFUL. INTERROGATED CDS, NO CURRENT FAULT OR FAULTS IN HISTORY FOUND. PERFORMED FREEDOM OF MOVEMENT CHECK IAW AMM TASK 27-10-00-710-801, 27-13-00-710-802, AND 27-61-00-710-801. ALL CONTROL SURFACES HAVE FULL MOVEMENT OF TRAVEL. FERRIED AIRCRAFT. C/W TO 201405051546, WIRING CHECKS GOOD. REMOVED FGM 1 IAW TC 6221101. INSTALLED SERVICEABLE FGM IAW TC 6221101. PERFORMED LLM RTS TEST IAW TASK CARDS 6221101 FOR NR 1 AND NR 2 FGM'S. RETURNED TO SERVICE.