Accident
A helicopter departed with a pilot and an aerial photographer for a mountain pass. On a hot day, the available engine power was insufficient for the climb required by the first selected route. The pilot then attempted a second route, which was 500 feet lower but still exceeded the helicopter's performance capability. As the helicopter climbed, its clearance above the rising terrain decreased to 300 feet, prompting the pilot to reverse course toward lower elevation. During this maneuver, the pilot failed to maintain adequate main rotor rpm, resulting in an uncontrolled descent and impact with the mountainside at 6,400 feet mean sea level. The density altitude at the time was approximately 8,600 feet.
Weight
At takeoff, the helicopter was 41 pounds over its maximum certificated gross weight. At the time of the accident, it was about 18 pounds below the maximum certificated gross weight.
Probable Cause
The National Transportation Safety Board determined the probable cause as the pilot's failure to maintain adequate main rotor rpm to sustain flight.