As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE LANDING FROM A HOVER, AS THE WHEELS TOUCHED DOWN A VIBRATION WAS FELT. PILOTS PULLED EACH ENGINE BACK SEPARATELY AND FOUND VIBRATION COMING FROM #2 ENGINE. AFTER AIRCRAFT SECURE MECHANICS FOUND A PIECE MISSING FROM #2 ENGINE TO MAIN GEAR BOX DRIVE SHAFT ASSY. PIECE WAS MISSING FROM OUTER TORQUE WHEEL AND NOT THE DRIVE SHAFT. PART WILL BE RETURNED TO THIS REPAIR STATION FOR INVESTIGATION. MANUFACTURE HAS BEEN NOTIFIED AND WILL PARTICIPATE IN INVESTIGATION.