HISTORY OF FLIGHT On October 31, 1999, about 0935 mountain standard time, a Cessna U206F, N902CT, registered to and operated by Stanley Air Taxi as a 14 CFR Part 135 on demand flight, collided with the terrain in a valley surrounded by mountains located about 21 miles west of Challis, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the commercial pilot and his three passengers were fatally injured. The flight had originated in Challis, about 15 minutes prior to the accident. The operator reported that the aircraft departed from Stanley, Idaho, about 0845, en route to Challis, to pick-up the passengers. The pilot was to then fly the passengers to the Triple Creek Ranch Airstrip, a private airstrip, for a hunting excursion. The owner of the airstrip reported that he witnessed the aircraft approach the airstrip from the west, for landing to the east. While on final approach, power fluctuations were heard. The aircraft touched down on the approach end of the strip, then bounced into the air to about 20 feet above ground level. The witness then heard the pilot apply corrective power for about three to five seconds before full power was applied. The aircraft continued to travel the length of the airstrip, gaining little altitude, before the witness lost sight of the aircraft beyond the trees at the upper end of the airstrip. The witness said he heard engine noise for about one minute longer. The registered owner/operator of the aircraft, who was also flying in the area at the time, reported that the winds were "windy and choppy" and that a front was moving through the area. Other pilots, communicating via the aircraft radio, were also reporting the weather conditions around the area at the various remote airstrips. The owner reported that prior to the departure of the flight, he spoke with the pilot about the wind starting to pick-up at the Stanley airport, and that if windy (at Triple Creek), take the passengers back to Challis. PERSONNEL INFORMATION At the time of the accident, the pilot held a commercial certificate for single-engine and multi-engine land aircraft, with an instrument rating. Stanley Air Taxi records indicate that the pilot began his employment with the operator in May 1999. A 14 CFR Part 135 Airmen Competency/Proficiency Check was satisfactorily accomplished on June 8, 1999. During the flight check, the pilot demonstrated normal and crosswind landings, a simulated powerplant failure landing, and a rejected landing. The operator records also indicate that the pilot completed company training which included, landings at the various airstrips that the operator provides service. The owner and chief pilot for Stanley Air Taxi reported that he personally flew with the pilot into Triple Creek, and instructed the pilot that a go-around was never to be performed at this airstrip. Company records and the pilot's flight logbook indicate that a total flight time of approximately 2,015 hours had been accumulated. Approximately 361 hours had been accumulated in the Cessna U206F. The flight logbook indicated that the pilot had landed at Triple Creek 25 times in the Cessna U206F, and seven times in the companies Cessna 182. AERODROME INFORMATION The airstrip alignment is approximately 9/27 degrees. The grass strip is 2,600 feet long and 25 feet wide. The elevation is 5,500 feet. The surface upslopes approximately 10 degrees to the east. The airstrip is surrounded by steep mountainous terrain. The owner of the airstrip reported that landing is to the east and takeoff is to the west. Takeoff to the east is not recommended due to rapidly rising terrain. WRECKAGE AND IMPACT INFORMATION The wreckage was located in Snowshoe Creek, a narrow valley bordered by high terrain that runs to the north from Triple Creek. The valley extends about two miles before ending at the base of mountainous terrain that rises steeply to about 8,000 feet. The wreckage was located on the east side of the valley floor, about one mile from the entrance. The elevation at the accident site is approximately 5,715 feet. Numerous trees surrounded the wreckage, however, no evidence of a tree strike was found. Documentation of the wreckage indicated that the aircraft collided with the valley floor in a near vertical attitude. The aircraft was positioned right-side up with the nose pointing to 270 degrees. An impact crater was noted about 16 feet in front of the nose of the airplane. All three propeller blades had separated from the hub and were found in this crater. The hub was broken and segmented. All three propeller blades displayed leading and trailing edge nicks and gouges. Chordwise scoring was noted to the blade backs. All three blades displayed "S" bending deformation. A long thin ground signature was noted extending on either side of the impact crater that was consistent with the length of both wings. At the end of the signature traveling to the south, the broken red lens light from the left wing was found. The horizontal portion of the pitot tube from the left wing was also found on this side of the ground signature near the impact crater. On the opposite side of the crater, the ground signature traveling to the north displayed white paint chip fragments. At the end of this signature, a small tree was bent over at its base, and broken from impact from the right wing tip. The entire length of the leading edges of both wings displayed rearward crushing. Both wings remained attached to the fuselage at the wing roots. The inboard section of both wings displayed heat signatures from the fire that consumed the fuselage and cockpit. The flaps and ailerons remained attached to their respective hinges. The inboard section of the right wing was more severely burned than the left. The inboard half of the right flap was destroyed by the fire. The flap actuator was inspected and it was determined that the flaps were extended between zero and ten degrees. Both fuel tanks were breached and contained no fuel. Control cables were traced from the fuselage to the wing tips. Due to impact damage, movement of the cables was not possible. The aft tail section was bent up and over the top of the empennage. The vertical stabilizer, rudder, left side horizontal stabilizer and elevator were completely destroyed by the fire. The right side horizontal stabilizer remained intact with the elevator and trim tab attached to their respective hinges. Control cable continuity was confirmed from the aft portion of the fuselage to the tail surfaces. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by F.J. Fantelli, MD, at Eastern Idaho Regional Medical Center, Idaho Falls, Idaho. Blunt trauma and laceration of the aorta secondary to deceleration was the pilot's cause of death. Toxicological samples were sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma City, Oklahoma, for analysis. The results of the analysis were reported as negative for all screened substances. ADDITIONAL INFORMATION The engine was inspected on November 10, 1999, at SP Aircraft, Boise, Idaho. Evidence of heat distress was noted to the aft section of the engine. The crankshaft was found to rotate easily with accessory gear and valve train continuity established. Compression was developed in each cylinder. Both magnetos produced a spark from the leads. The spark plugs displayed normal operating signatures. Fuel was present in the line to the pressure gage. The fuel manifold was intact. The screen was clear of contaminants and the diaphragm was intact. All injector lines and nozzles were unobstructed. The fuel pump drive was intact, and the pump was free to rotate. The vacuum pump would not turn. Upon further inspection, the rotor was found cracked. The vanes were intact. The oil filter displayed heat distress and was destroyed. The fuel screen was clear. The oil sump was compromised. Traces of oil were present. The wreckage was released to the owner's representative on November 16, 1999. The wreckage was moved to and stored by SP Aircraft at a facility near Boise, Idaho.