On December 7, 2000, about 1015 Pacific standard time, an Aerospatiale AS-350-BA helicopter, N355NT, was substantially damaged during a collision with a rock and a hard landing from a pinnacle approach near Henderson, Nevada. Neither the commercial pilot, airline transport rated company check pilot, nor the Federal Aviation Administration (FAA) inspector was injured. Visual meteorological conditions prevailed for the instructional flight operating under 14 CFR Part 91, and a company flight plan was filed. The flight originated at Las Vegas, Nevada, about 1005. The purpose of the flight was an FAA monitored 14 CFR Part 135 check ride of a company pilot by the company check airman. According to the FAA inspector who was onboard and monitoring the check ride, while performing a pinnacle approach procedure into an unimproved site, the right front portion of the helicopter's skid collided with a large rock. This occurred with some forward speed. The resultant hard landing caused substantial buckling of the tailboom assembly. The operator did not file a Pilot/Operator Accident Report, NTSB form 6120.1/2.