NTSB Identification: SEA07FA223.
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Nonscheduled 14 CFR
Accident occurred Thursday, August 02, 2007 in Easton, WA
Probable Cause Approval Date: 08/28/2008
Aircraft: Robinson R44 II, registration: N7531D
Injuries: 4 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The helicopter was departing from a clear cut area in forested mountainous terrain at an elevation of 4,961 feet. A witness observed the helicopter lift off vertically, oriented in a southerly direction, to an altitude of about 40 feet before turning 90 degrees to the left and proceeding down the hillside to the east. The helicopter then began to sway back and forth after traveling about 100 to 150 feet, then it impacted the ground in a nose low, left bank attitude. The witness stated that the wind was switching around during the morning, and that it was blowing down slope toward the east at the time of the accident. The closest weather reporting facility, which was located 8 miles west of the accident site, reported winds gusting out of the west to 16 knots. No evidence of any preimpact anomalies were found during the post accident examination that would have precluded normal operation. During the accident flight the helicopter was being operated 77 pounds over the maximum gross weight for an Out of Ground Effect hover for the existing conditions. The helicopter was being operated in a high density altitude environment, which was computed to be 6,841 feet mean sea level.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's improper planning/decision in attempting a downwind takeoff under high density altitude conditions that resulted in a loss of control and impact with terrain. Contributing to the accident were the helicopter's gross weight in excess of the maximum hover out of ground effect limit, a high density altitude, and the gusty tailwind. Full narrative available
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