THE ACCIDENT HELICOPTER, OPERATING AS AN AERIAL SIGHT-SEEING CONCESSION, FAILED TO SUSTAIN FLIGHT AND LANDED HARD AFTER ATTEMPTING A DOWNWIND TAKEOFF FROM A RAISED HELIPAD (PINNACLE). THE INVESTIGATION SHOWED THAT THE HELICOPTER WAS TOO HEAVILY LOADED TO HOVER OUT OF GROUND EFFECT AT THE DENSITY ATTITUDE (2500 FEET) OF THE ACCIDENT SITE AND THE CENTER OF GRAVITY WAS OUTSIDE OF THE ALLOWABLE RANGE. THE PILOT STATED DURING AN INTERVIEW THAT HE PERCEIVED A POWER LOSS AFTER CLEARING THE PINNACLE AND WAS UNABLE TO MAINTAIN ROTOR RPM WITH THE THROTTLE FULL OPEN. POST ACCIDENT INSPECTION OF THE HELICOPTER SHOWED NO DEFECTS IN THE AIRFRAME OR POWERPLANT. ACCORDING TO WITNESSES AT THE SCENE THE ACCIDENT, THE HELICOPTER TOOK OFF FROM THE PINNACLE IN A GENERALLY EASTERLY DIRECTION. WHEN THE PILOT WAS ASKED ABOUT THE WINDS AT THE TIME OF THE TAKEOFF, HE DESCRIBED THEM AS WESTERLY AT APPROXIMATELY 6 TO 8 KNOTS.