Incident Overview
A pilot flying a helicopter to a hospital helipad encountered difficulties during the final phase of the approach. The helipad, approximately 200 square feet in area, was surrounded by hazards: 40-foot-high wires on the north side and trees ranging from 35 to 50 feet in height on the remaining sides. A windsock indicated westerly to southwesterly winds of 3 to 5 knots.
Approach and Descent
The pilot initiated an approach from the southwest, descending vertically toward the helipad. The airspeed was below 10 knots as the pilot attempted to stop the rate of descent. When additional power was applied, the helicopter shuddered and yawed to the right. The pilot reported that further collective pitch input seemed to have no effect on slowing the descent; instead, the rate of descent appeared to increase.
Loss of Control and Impact
Determining that there was insufficient space to fly out of the confined area, the pilot applied all remaining collective pitch before impact. No master caution lights, annunciator panel warnings, or audio tones were observed during the event.
Related Manual Information
A helicopter aerodynamics manual described conditions conducive to settling with power, including a vertical or near-vertical descent rate of at least 300 feet per minute, engine power between 20 and 100 percent, and a downwind steep approach.