What was found
OBSERVED UP TO 50 KNOT AIRSPEED DIFFERENCE BETWEEN CA AND ISI DURING CRUISE @ FL350, ALSO RECEIVED MACH TRIM CAUTION, RUD LIMIT FAULT 2, R FADEC FAULT 2, AND L FADEC FAULT 2 MESSAGES. FOLLOWED QRH FOR UNRELIABLE AIRSPEED. R/R ADC #1 IAW CRJ900 AMM 34-13-01. BITE TEST GOOD. OPS TEST GOOD. LEAK CHECK PERFORMED, NO LEAKS DETECTED AT THIS TIME.