As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE IN CRUISE BACK TO BASE, CREW ENCOUNTERED AIRFRAME VIBRATION FROM THE AFT CABIN, FOLLOWED BY THE RT GENERATOR FAIL LIGHT 10 MINUTES LATER. CREW CONFIRMED LOSS OF RT GENERATOR, AND DECLARED AN EMERGENCY DUE TO THE INTENSITY OF VIBRATION. A/C LANDED WITHOUT INCIDENT. ON DISASSEMBLY OF UNIT, DISCOVERED CUMMUTATOR BEARING DESTROYED. CAUSE OF FAILURE IS UNDER INVESTIGATION. THERE WAS ONLY 406 HRS ON THE BEARING SINCE REPLACEMENT.