WHILE ATTEMPTING TO DEPART ON A VFR PERSONAL FLIGHT, CONTROL OF THE HELICOPTER WAS LOST AND IT STRUCK THE GROUND. NEITHER THE FLYING PILOT NOR THE OWNER/PIC, OCCUPYING THE LEFT FRONT SEAT, HELD A ROTORCRAFT-HELICOPTER RATING. THE PIC HAD PREVIOUSLY FLOWN HELICOPTERS, INCLUDING THE ACCIDENT HELICOPTER. THE AIRCRAFT DID NOT HAVE DUAL CONTROLS. THE OWNER/PIC AND THE PILOT, WHO WAS ALSO A FAA DESIGNATED MEDICAL EXAMINER, INITIALLY REPORTED TO AUTHORITIES THAT THE PASSENGER FELL OUT OF A PICK-UP TRUCK. LATER, THE OWNER/PIC REPORTED TO THE SAFETY BOARD THAT HE WAS PREFLIGHTING THE HELICOPTER WITH THE ENGINE RUNNING WHEN IT ROLLED OVER. THE POST-ACCIDENT INVESTIGATION REVEALED THAT THE HELICOPTER STRUCK THE GROUND UNDER HIGH POWER IN A LEFT, NOSE DOWN ATTITUDE AND THE EVIDENCE INDICATED THAT THE PILOT FLYING WAS THE PILOT WITH NO PREVIOUS HELICOPTER EXPERIENCE.