The pilot's failure to maintain adequate main rotor speed during the intentional autorotation, and his subsequent inability to reduce the descent rate prior to impact. A contributing factor was the intentional autorotation initiated by the pilot.

The pilot's failure to maintain obstacle clearance resulting in a collision with a fence.

THE STUDENT PILOT'S IMPROPER EXECUTION OF THE LANDING PROCEDURE RESULTING IN DYNAMIC ROLL-OVER OF THE HELICOPTER.