What was found
(CAN) "AFTER T/O MACH TRIM & STAB TRIM CAUTION MESSAGES ILLUMINATED. DECLARED EMERGENCY AND LANDED. "PERFORMED OPS CHECK. NO DEFECTS FOUND. RESET PER FIM AND OPS CHECKED GOOD. RETURNED TO SERVICE. 2ND FLT "AFTER T/O MACH TRIM & STAB TRIM CAUTION MSGS ILLUMINATED. WOULD NOT RESET. DECLARED EMERGENCY AND LANDED BACK AT TUL. "SENT ROAD CREW FROM CVG. COULD NOT DUPLICATE PROBLEM. R&R'D HSTCU & MCU AS PRECAUTIONARY MEASURE: FOUND BOTH LEFT & RIGHT HORIZONTAL STAB VISORS CRACKED. R&R'D VISORS. ON FERRY FLT BACK AFTER ABOVE MAINT ACTION PROBLEM DID NOT REOCCUR.