What was found
DURING CRUISE, IAS MISCOMPARE ALERT CAME ON BOTH CAP & FO`S PFD. AIRSPEED MISCOMPARE STARTED AT 4 KTS THEN WENT TO APPROX 50 KTS MISCOMPARE BETWEEN BOTH PFD'S, FOLLOWED BY AUTO THROTTLES DISENGAGED, AUTOPILOT DISENGAGED & FLIGHT DIRECTOR DISAPPEARED. ALTITUDE MISCOMPARE BY 450', SEL ELEV FEEL MAN, SEL FLAP LIM OVERRIDE. AFTER TROUBLESHOOTING SYS IAW QRH, DECIDED THAT CADC 2 WAS BAD & USED QRH TO TRANSFER BOTH DISPLAYS TO CADC 1, FD1 & AP2. ALL SYS ON CADC 1 CAME BACK, NO ASSOCIATED PROBLEMS. INSPECTED ALL PITOT & STATIC PORTS. NO BLOCKAGE FOUND. CHECKED & ENSURED ALL AIR DATA MODULE CONNECTIONS WERE SECURED IAW AMM 34-16-01-4. REPLACED NR 2 ADIRU IAW AMM 34-43-03-4, CHECKED SATISFACTORY.