What was found
DURING CLIMB OUT THE RT GEN ANNUNCIATOR ILLUMINATED & NO OUTPUT WAS OBSERVED ON THE AMMETER. CHECKLIST PROCEDURES WERE FOLLOWED & THE ACFT MADE AN UNEVENTFUL LANDING BACK AT DEPARTURE AIRPORT & THE ACFT WAS TURNED OVER TO MX. INITIAL INVESTIGATION NOTED THAT THE BITE INDICATOR ON THE RT GCU WAS INDICATING A GND FAULT & AN ABNORMAL AMOUNT OF STAINING WAS NOTED COMING FROM THE GEN EXHAUST ON THE RT ENG COWL. INSPECTION OF THE STARTER & GEN WHILE STILL INSTALLED REVEALED PITTING & SCORING ON THE COMMUTER. AFTER REMOVAL OF THE STARTER & GEN IT WAS DISCOVERED THAT THE FWD BEARING HAD FAILED WITH THE ABNORMAL PLAY ALLOWING THE COOLING FAN TO STRIKE THE HOUSING & THE RESULTANT DEBRIS GETTING INTO THE BRUSH & COMMUTER AREA, SHORTING, THUS CAUSING THE GND FAULT. THE STARTER & GEN WAS REPLACED WITH AN OVERHAULED UNIT & THE GCU WAS RESET. GND OPERATIONAL & PARALLELING CHECKS WERE GOOD. THE FAILED UNIT HAD 364 HOURS TO GO UNTIL REQUIRED OVERHAUL, 1,000HR INTERVAL.