What was found
DURING FLIGHT 2473 MKE-OMA THE CREW CONTACTED MAINTENANCE AND REPORTED A LEFT ALTERNATOR FAIL INDICATION. THE CREW SUCCESSFULLY RESET THE SYSTEM IN FLIGHT ONLY TO HAVE THE PROBLEM RETURN SHORTLY. IT WAS DETERMINED THAT THE AIRCRAFT SHOULD PERFORM AN AIR TURNBACK TO MKE. A SHORT TIME LATER THE CREW REPORTED A LEFT ENGINE VIBRATION. THE FLIGHT WAS DIVERTED TO MSN. MAINTENANCE INSPECTED THE AIRCRAFT AND FOUND THE LEFT ALTERNATOR BEARING AND PART OF THE END CAP HAD BEEN SEVERELY DAMAGED. THE VIBRATION WAS MOST LIKELY CAUSED BY THE ARMATURE SPINNING LOOSELY IN THE ALTERNATOR CASE CAUSING MORE DAMAGE.