What was found
FLT 4752 - ON CLIMB-OUT FROM MYR, CAPTAIN RECEIVED BOTH 'STAB TRIM' AND 'MACH TRIM' CAUTION MESSAGES THE CAPTAIN WAS ABLE TO RE-ENGAGE THE STAB AND MACH TRIM ONLY AFTER ENGAGING THE AUTOPILOT. THEN THE 'AP PITCH TRIM INOP' AND 'AP TRIM NOSE DOWN' CAUTION MESSAGES ILLUMINATED. AT THIS POINT AN EMERGENCY WAS DECLARED. AIRCRAFT DIVERTED TO CHS AND HAD AN OVER GROSS LANDING WITHOUT INCIDENT. MAINTENANCE PERFORMED AN OVER GROSS LANDING INSPECTION. NO DEFECTS WERE NOTED. MAINTENANCE ALSO REORIENTED THE NR 2 ATTITUDE HEADING REFERENCE SYSTEM. OPS CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE. (M)