On September 21, 2005, approximately 1650 Pacific daylight time, a Cessna 170A, N9527A, impacted power lines crossing the Pend Oreille River about one mile north of Box Canyon Dam, near Ione, Washington. The airline transport pilot, who was the sole occupant, received fatal injuries, and the aircraft, which is owned and operated by the pilot, sustained substantial damage. The flight was operating in visual meteorological conditions at the time of the accident. The aircraft was last seen at the Lake Sullivan State Airstrip, and it reportedly departed there about 30 minutes prior to the accident. It is believed that the pilot was on a local pleasure flight, with an intended ultimate return to Lake Sullivan. There was no report of an ELT activation. No flight plan had been filed. According to witnesses, the aircraft was first noticed going to the north, flying low over the trees along the side of the Pend Oreille River. It then reversed course and headed to the south at 100 feet or less above the river. The aircraft was then seen to impact a pair of unmarked power transmission wires that run across the river about one mile north of the Box Canyon Dam. Immediately upon contacting the power lines, the aircraft's pitch attitude rotated to a near vertical position, and it descended nearly straight down into the river. In less than two minutes after hitting the surface of the river, the aircraft sank in about 10 feet of water. It was later determined that the power lines were between 80 and 90 feet above the surface of the river. An inspection of the aircraft after it was recovered from the river revealed wire strike abrasions on the propeller, the lower portion of the fuselage just aft of the door frames, and at the point where the vertical stabilizer leading edge intersects the fuselage. Control continuity was established to the elevator, and there was no indication that there had been any anomaly associated with the engine. An autopsy performed by the Pend Oreille County Corner determined that the pilot died as a result of blunt force impact to the head and torso, and that the cause of death was accidental. A forensic toxicology performed by the FAA's Bioaeronautical Science Research Laboratory was negative for carbon monoxide, cyanide, ethanol, and screened drugs.