History of Flight
On July 25, 2011, about 1438 Pacific daylight time, a Sikorsky S-55B helicopter, registered as N5663, sustained substantial damage after colliding with powerlines and impacting terrain near Chelan, Washington. The helicopter was owned by Golden Wings Aviation and operated under 14 CFR Part 91. The commercial pilot, the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from a staging area near the accident site about 10 minutes prior.
A witness reported that the helicopter was flying over a cherry orchard from south to north and had just completed a left turn when it struck the powerline. The witness observed the helicopter descend out of view after the collision and then saw a large cloud of black smoke near the maneuvering area. The helicopter was contracted to dry cherries after a rain shower.
Personnel and Aircraft Information
The 22-year-old pilot held a commercial pilot certificate with rotorcraft-helicopter and instrument ratings, as well as a flight instructor certificate with rotorcraft-helicopter rating. His most recent first-class medical certificate was issued May 5, 2011, with a requirement to wear corrective lenses. His logbook was not recovered. The operator reported the pilot had 1,192 total rotorcraft-helicopter hours, with 50 hours in the accident make and model.
The accident helicopter, a Sikorsky S-55B, was manufactured in 1959, powered by a Wright R-1300 radial engine rated at 800 HP, with a three-blade main rotor and conventional tail rotor. Maximum gross takeoff weight was 7,200 pounds. Its most recent annual inspection was completed June 1, 2011, at a total airframe time of 7,397 hours; engine time since overhaul was 13 hours.
Meteorological and Wreckage Information
At 1455, weather at Pangborn Memorial Airport, Wenatchee, about 35 miles south, included winds from 300° at 8 knots, clear skies, 10 miles visibility, temperature 23°C, dew point 14°C, and altimeter 29.91 inHg.
Examination showed the helicopter impacted terrain in a nose-low attitude about 45 feet south of the powerlines, followed by a postcrash fire. Initial impact involved power delivery lines running northwest to southeast along the orchard's northern perimeter. The span between two support poles was about 800 feet, with four wires: three coplanar at about 50 feet and one below at about 40 feet. Each wire was a bundle of six individual wires.
The main wreckage lay within a burn area. The cockpit, instrument panel, pedestal, and cabin sustained extensive impact and thermal damage. The three rotor blades remained attached to the hub. Powerline wires were wrapped 3-4 times around the main rotor swash plate and mast. All dampeners detached; two pitch change links detached, one bent. Fractures on the mast assembly appeared from overstress. Striation marks from wire strike were on leading edges of blades A and C. Numerous wire strands with tension-like failure were found. A postaccident examination found no preimpact mechanical failure precluding normal operations.
Medical and Pathological Information
Toxicological testing by the FAA's Civil Aerospace Medical Institute on the pilot was negative for cyanide, ethanol, and tested drugs. An autopsy on July 26, 2011, at Central Washington Hospital attributed the cause of death to asphyxia due to inhalation of products of combustion.
Additional Information
Review of the pilot's cellular phone records showed his phone was active on the accident day, but no outgoing text messages or calls were documented between 1430 and the accident time.