As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE MAIN TRANSMISSION WAS DELIVERED FOR OVERHAUL. THERE WAS NO NOTICE ABOUT AN INCIDENT OR A CHIP WARNING. CHIP DETECTOR AND OIL FILTER WERE CLEAN. AT THE BEGINNING OF THE DISASSEMBLY, MECHANIC NOTED THAT THE TAILROTOR DRIVE DIDN’T MOVE WHEN THE INPUT FLANGE WAS TURNED. AFTER REMOVING THE UPPER HOUSING, A SEVERE DAMAGE OF THE TAIL ROTOR DRIVE PINION AND THE ASSOCIATED ROLLER BEARINGS WAS DETECTED. THE BEARING WAS CRACKED AND THE TEETH OF THE PINION WERE SEVERELY DEFORMED. THERE WERE MANY METAL CHIPS INSIDE THE GEARBOX. (K)