History of Flight
On November 6, 2013, at approximately 0910 mountain standard time, a Cessna U206F (registration N206KL) impacted terrain about 12 miles east of Donnelly, Idaho. The commercial pilot and two passengers were fatally injured; the airplane was destroyed. The airplane was registered to Wilderness Aircraft I LLC and operated by McCall Aviation Inc. under 14 Code of Federal Regulations Part 135. Visual meteorological conditions prevailed, and the flight operated on a company flight plan. The flight originated from McCall Municipal Airport (MYL) at 0900 with a destination of Lower Loon Creek Airport (C53) in Challis, Idaho.
The accident airplane was one of three departing MYL for C53. Pilots from the other two airplanes reported that, prior to departure, all three pilots checked the weather and reviewed weather webcams positioned throughout the passes. They also contacted people on the ground and in the air for weather descriptions. The accident pilot departed first, followed by the other two airplanes. The second and third pilots took a northern route commonly used when weather is not perfect. The accident pilot chose a different route to the south, which was not abnormal, but he did not explain his choice. During the flight, the three pilots communicated via radio. The accident pilot reported that the first route he attempted was blocked, so he turned around and flew further south. The last radio transmission heard from him indicated he was clear in the south fork of the Salmon River.
A portable GPS unit recovered from the wreckage was sent to the NTSB vehicle recorders laboratory. The data showed the airplane departed MYL to the southeast, then turned east toward the mountains. The track entered the mountains, proceeded south along a valley, then flew west and exited the mountains. It continued south along a ridgeline before turning east and reentering the mountains. In the final 40 seconds, the airplane turned northeast, then southeast, then southwest, following a horseshoe-shaped ridgeline with elevations between 8,000 and 8,200 feet. As the airplane began the northeast turn, it was at 8,150 feet with a groundspeed of 128 knots. During the southeast heading, groundspeed decreased from 145 to 71 knots, then increased to 89 knots, with no altitude change noted. After turning southwest, the final data point recorded 8,150 feet and 152 knots.
Personnel Information
The pilot, age 66, held a commercial pilot certificate with airplane single- and multi-engine land privileges and an instrument rating issued December 15, 2007. His most recent second-class medical was issued December 18, 2012, with no limitations or waivers. He was hired by McCall Aviation in May 2008 and flew all seasons. His most recent proficiency check occurred July 29, 2013, for single-engine airplane. As of September 13, 2013, he reported 3,841 total hours, with 2,158 in the accident make and model. This was his first flight after a day off.
Aircraft Information
The accident airplane, a Cessna U206F, serial number U20602655, was manufactured in 1975 and equipped with a Continental IO-550F engine. The most recent maintenance was completed on October 23, 2013, at a total time of 16,501.4 hours, which included replacement of the alternator belt and installation of bolts, springs, and washers to the left exhaust stack. On October 3, 2013, at 16,493.00 hours, the airplane underwent a phase check maintenance schedule. On September 30, 2013, at 16,489.10 hours, a new bladder fuel tank was installed in the right wing.
Meteorological Information
The nearest weather reporting facility, MYL, located about 14 miles northwest of the accident site, reported at 0851: calm wind, 9 statute miles visibility, few clouds at 300 feet agl, broken clouds at 2,500 feet agl, and overcast clouds at 3,200 feet agl. Temperature was -1°C, dewpoint -2°C, altimeter 30.29 inHg.
The other two pilots reported that weather was not perfect. The valley at MYL was good and began clearing to a broken overcast. Along their route, weather was marginal with low clouds in various locations, but it cleared as they neared C53. They did not need to divert.
Due to the accident site location, weather reporting stations and products were limited. Satellite imagery could not show low-level clouds due to a mid-level cloud layer at 15,000 feet. Other sources could not show cloud conditions. AIRMETs for IFR and mountain obscuration were issued, but there was no indication those conditions occurred near the accident site.
A weather model simulating relative humidity over the accident site indicated that lower altitudes likely had much lower visibility with relative humidity above 98%. An algorithm using satellite, radar, surface, and pilot reports calculated the probability of icing as "light" to "moderate" severity with high probability.
Wreckage and Impact Information
The airplane came to rest about 100 feet from the top of the westernmost ridgeline of a horseshoe-shaped ridge, on the inside of the horseshoe with a heading consistent with the opening. Terrain was steep, heavily treed, and covered with about two and a half feet of snow, some fresh. The first identified debris was the inboard portion of the right elevator, found about 20 feet south of the main wreckage at the base of a small tree not topped. Between this point and the main wreckage were several topped trees. The wreckage came to rest between two trees at a heading of about 299°. One tree sustained about 10 feet of scratching and scoring; the airplane wrapped around this tree, severing the fuselage just aft of the cabin. The engine, forward fuselage, cabin, and left wing were on the northeast side; the aft fuselage and empennage on the northwest side.
The forward fuselage and cabin were upright but angled about 45° onto the right side, heavily damaged. The engine was intact and mostly buried in snow; one magneto had separated 3 feet ahead. The cabin sustained forward crushing; the instrument panel was heavily damaged. Left seat control yoke cables were still attached. The left wing was mostly separated, twisted upside down, resting on top of the fuselage. A 4-foot section of a 10-inch diameter tree was lodged in the left wing trailing edge. The right wing was completely separated at the root; the inboard portion at the base of the tree, covered in snow and ice; heavy organic debris at the outboard fracture. The outboard portion was not located. The empennage had heavy crush damage; vertical stabilizer and rudder accordion-crushed forward; left horizontal stabilizer separated and located 10 feet west.
Additional Information
A postaccident airframe and engine examination by NTSB, FAA, Textron Aviation, Continental Motors, and McCall Aviation revealed no anomalies that would have precluded normal operations.
Airframe Examination: All components were present except the outboard right wing. Flight control continuity was established; cable breaks were consistent with tension overload or cut by recovery crew. Flap jackscrew indicated flaps retracted. Elevator trim position could not be determined. Fuel selector valve was positioned on the right tank. Inside the right fuel bladder was mostly clear with small particles.
Propeller: The propeller hub fractured and separated from the flange; blades separated from the hub. None had leading impact damage. One blade bent forward 10° midspan with chordwise scoring on the cambered side. The second blade twisted 20° at outboard six inches, leading edge aft. The third blade bent aft 10° in a large radius bend starting 10 inches from hub, with outboard seven inches bent aft 45° in a small radius bend.
Engine Examination: Engine remained attached by fuel lines and control cables; no catastrophic failure. Both magnetos separated; left magneto sparked on three of six towers when manually rotated; right sparked on all six. Spark plugs showed normal wear. Gascolator screen clear except small pinkish-gray lint. Engine-driven fuel pump rotated freely. Throttle body/fuel metering unit fractured and deformed; throttle plate in full open position; throttle and mixture controls attached. Fuel inlet screen covered in pinkish-gray lint; light visible through debris. Oil pump and filter showed no anomalies. Crankcase impact-damaged; cylinder #5 displaced. All cylinders showed no distress or oil starvation. Starter adapter needle bearing boss had witness mark consistent with crankshaft gear teeth. Crankshaft visibly distorted to left, preventing rotation; no evidence of oil starvation or operational distress. Camshaft intact but bent; no corrosion, excessive wear, or rubbing.
Magneto Examination: Left magneto tested at Aircraft Magneto Services; only one of six terminals sparked. Disassembly revealed distributor block-rotor-screws bent aft; rotor gear fractured in half from overload.
Fuel Metering Unit Examination (NTSB Materials Lab): Debris on inlet screen analyzed; gray material matched dimethylsiloxane (silicones used in lubricants, fire sleeving, sealants). Red fiber matched cellulose (natural fibers like wool and cotton).
Medical and Pathological Information
An autopsy performed November 9, 2013, by the Valley County coroner's office indicated the pilot's cause of death was severe blunt force trauma.
The FAA Civil Aerospace Medical Institute performed forensic toxicology on pilot specimens. Results were negative for carbon monoxide, cyanide, and tested drugs. Ethanol was detected: 22 mg/dL in liver, 100 mg/dL in muscle, 30 mg/dL in heart, and 12 mg/dL in lung. N-Propanol was detected in the liver.