What was found
AIRCRAFT WAS GROUNDED. CMD A AP ON, CA F/O ON DURING DESCENT F/O AIRSPEED REF BUG INCREASED AND SEPARATED FROM CA STANDBY AIRSPEED INDICATIONS. F/O`S INDICATION INCREASED TO VMO. F/O`S AIR SPEED INDICATION RETURNED TO MATCH CAPATAIN`S STANDBY INDICATION WHEN VNAV PATH DISENGAGED BY SWITCHING TO LVL CHG. REPLACED FLIGHT CONTROL COMPUTER A AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK, PER AMM 22-11-33 (AALA202008219017). REPLACED FLIGHT MANAGEMENT CONTROL SYSTEM TRANSFER RELAYS R475 (AALA202009229018) AND R475 (AALA202009229019). ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK, PER AMM 34-61-04.