What was found
(CAN) OPERATOR REPORTED TO BOMBARDIER FIELD SERVICE THAT THE LEFT ESSENTIAL AND MAIN ELECTRICAL BUS (L ESS BUS FAIL, L MAIN BUS FAIL) CAUTION MESSAGE WAS POSTED ON EICAS AFTER DEPARTURE. THE FLIGHT CREW FOLLOWED THE AIRPLANE FLIGHT MANUAL PROCEDURES AND LANDED SAFELY. A POST INCIDENT OBSERVATION BY THE AUTHORITIES NOTED THAT THE ELECTRICAL FAULT CAUSED THE CVR AND FDR NOT TO RECORD ANY DATA. THE OPERATOR INSPECTED THE ELECTRICAL SYSTEM AND FOUND A PROTECTION PCB CARD FAILURE AND REPLACED THE CARD.