NTSB Identification: SEA07LA041.
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Accident occurred Thursday, January 04, 2007 in Lyman, WA
Probable Cause Approval Date: 04/25/2007
Aircraft: Hughes 369D, registration: N1088G
Injuries: 1 Serious.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot made two long-line movements of cargo in light dry snow. After completing the second load, the pilot noticed that the snow had turned wet and heavy, and he told the ground crew that he was leaving the area. As he turned to depart the area, one of the ground crew radioed him and said that he was going to pass near one of the loads, and suggested that he pick it up. The pilot maneuvered toward the load, and entered into a hover to swing the long-line hook forward. Just as he entered the hover, the engine lost power, and the pilot delayed his emergency autorotation to allow the ground crew person to find cover. Because the rotor system energy decayed during the pilot's intentional delay of the autorotation, he was unable to control the descent, and the helicopter settled onto the terrain at an excessive rate of descent. The pilot stated that when he changed the angle of attack to put the hook in the right location, he believes a layer of wet snow and ice crystals lifted off the canopy and entered the engine particle separator, leading to a loss of engine power. A postaccident inspection did not reveal evidence of any system malfunction or anomaly.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's intentional flight into adverse weather conditions, which resulted in a loss of engine power during hover due to snow and ice ingestion. Factors associated with the accident are the pilot's delayed remedial actions, and snow and icing conditions.

Full narrative available

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