What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS AT START OF DESCENT AT FL310, THE A/P KICKED OFF AND WE GOT A CADC NR 1 FAIL MESSAGE. BOTH CA AND F/O AIRPSEEDS WENT TO 240 KTS WHILE STANDBY WAS AT 290 KTS. SWITCHING TO CADC NR 2 WAS NO HELP SO WE RAN THE AIRSPEED UNRELIABLE CHECKLIST. RAT WAS -11 WITH RIME ICE. APPROX FL190 ALL SPEED AGREED AND BACK TO NORMAL. MAINTENANCE REMOVED & REPLACED CAPT. & F/OS PITOT STATIC PROBES IAW AMM 34-11-02. REPLACED NR 1 & NR 2 CADCS IAW AMM 34-16-01. ALL CHECKS OK. SEE SDR AALA201905139050.