What was found
(CAN) AFTER DEPARTING WITH FMGC 2 UNDER MEL THE CREW REPORTED THAT FMCG 1 HAD ALSO FAILED. THE FLIGHT RETURNED TO YVR AND LANDED APPROXIMATELY 3000KG OVERWEIGHT. NO EMERGENCY WAS DECLARED. RESOLUTION NAV DATA SOFTWARE FOUND CORRUPT---LAST MONTHS SOFTWARE RELOADED AS PER AMM 22-70-00-610-008. CAT III LAND AND AFS TESTS C/O SERVICEABLE AS PER AMM 22-97-00 PB501 AND 22-96-00 PB 501.