What was found
UPON INTIAL ENGAGEMENT OF AUTO PILOT B, YOKE SNAPPED TO THE LEFT TO 4 DEGREES ON AILERON TRIM SCALE, THEN OPERATED NORMALLY. TRIED TO ENGAGE/DISENGAGE MULTIPLE TIMES - SAME RESULT. AUTO PILOT A OPERATES NORMALLY WITH NO SNAP ON INITIAL ENGAGEMENT. VERY SUBTLE BANK OF A/C IF AT ALL. DID NOT RE-ENGAGE AUTO PILOT B FOR REMAINDER OF FLIGHT. GROUNDED - YES. (RESOLVED ON W/O: 1963076 TASKCARD: N/R-00001 ) ACCOMPLISHED FIM 22-11 TASK 801. ALL TESTS PASS, OP TEST NORMAL. CLEARS MEL 22-1F & 22-99B. PLACARDS REMOVED, SEAMC.