What was found
(CAN) DURING CRUISE, AUTOPILOT DISENGAGED, ELEVATOR FEEL CAUTION AS WELL AS ATT FAIL, HDG FAIL, CUE, IVSI FAIL DISPLAYED ON PFD NR 2 AND MFD NR 2. CHANGING EFIS ADC SOURCE DID NOT CORRECT INDICATIONS. PAN DECLARED. CDS INTERROGATED FOR PREVIOUS LEG FAULTS AND "NO DATA FROM AHRS 2" WAS LOGGED. NR 2 ATTITUDE HEADING REFERENCE UNIT WAS REPLACED BY MAINTENANCE AND TESTED SERVICEABLE. THE AHRU HAD BEEN INSTALLED SINCE NEW AIRCRAFT DELIVERY. THE AIRCRAFT WAS SUBSEQUENTLY RELEASED FOR SERVICE.