What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS PITOT STATIC FAILURE AT FL310 WITH UNRELIABLE AIR SPEED AND AUTO PILOT DISENGAGED, COULD NOT DETERMINE WHICH SIDE WAS INCORRECT. MACH TRIM INOP AND AN OVERSPEED INDICATION WAS RECEIVED. MAINTENANCE REMOVED AND REPLACED #1 DIGITAL AIR DATA COMPUTER IAW AMM 34-16-01. ACCOMPLISHED RTS, TEST PASSED GO. ACCOMPLISHED PITOT/STATIC LEAK CHECK, OK IAW AMM 34-11-00. ACCOMPLISHED OVERSPEED INSPECTION IAW AMM 05-51-05, NO DAMAGE NOTED.