What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Instructor pilot and customer pilot performing recurrent training maneuvers. The instructor pilot demonstrated autorotation manuevers followed by repetitions by the customer pilot (no full touchdowns). Previously performed four straight in autorotations with no issues, then performed three 180 degree autorotations (customer pilot flying). On fourth 180 autorotation with customer pilot flying neither pilot noticed the throttles were still in idle during the manuever. When the aircraft was flared the nose dropped and the pilots made a run on landing, skidding approx 25 feet. On egress of the aircraft they noticed the main rotor had contacted the tail rotor drive shaft and cover and the aft cross tube was splayed wider than normal.
As the FAA filed it
INSTRUCTOR PILOT AND CUSTOMER PILOT PERFORMING RECURRENT TRAINING MANEUVERS. THE INSTRUCTOR PILOT DEMONSTRATED AUTOROTATION MANUEVERS FOLLOWED BY REPETITIONS BY THE CUSTOMER PILOT (NO FULL TOUCHDOWNS). PREVIOUSLY PERFORMED FOUR STRAIGHT IN AUTOROTATIONS WITH NO ISSUES, THEN PERFORMED THREE 180 DEGREE AUTOROTATIONS (CUSTOMER PILOT FLYING). ON FOURTH 180 AUTOROTATION WITH CUSTOMER PILOT FLYING NEITHER PILOT NOTICED THE THROTTLES WERE STILL IN IDLE DURING THE MANUEVER. WHEN THE AIRCRAFT WAS FLARED THE NOSE DROPPED AND THE PILOTS MADE A RUN ON LANDING, SKIDDING APPROX 25 FEET. ON EGRESS OF THE AIRCRAFT THEY NOTICED THE MAIN ROTOR HAD CONTACTED THE TAIL ROTOR DRIVE SHAFT AND COVER AND THE AFT CROSS TUBE WAS SPLAYED WIDER THAN NORMAL.