Hayden-Yampa Valley

The pilot performed an instrument approach to the runway with an approaching winter storm. A review of on-board global positioning system (GPS) data indicated that the airplane flew through the approach course several times during the approach and was consistently below the glideslope path. The airplane continued below the published decision height altitude and drifted to the right of the runway’s extended centerline. The GPS recorded the pilot’s attempt to perform a missed approach, a rapid decrease in ground speed, and then the airplane descend to the ground, consistent with an aerodynamic stall. Further, the airplane owner, who was also a passenger on the flight, stated that, after the pilot made the two “left turning circles” and had begun a third circle, he perceived that the airplane “just stalled.” An examination of the airframe and engine did not detect any preimpact anomalies that would have precluded normal operation. The airplane’s anti-ice and propeller anti-ice switches were found in the “off” position. A review of weather information revealed that the airplane was operating in an area with the potential for moderate icing and snow. Based on the GPS data and weather information, it is likely that the airframe collected ice during the descent and approach, which affected the airplane’s performance and led to an aerodynamic stall during the climb.

The pilot had filed an instrument flight rules flight plan with a planned departure time of 0700 in order to arrive at his intended destination in time for a planned engagement. He and his passenger arrived at the airport approximately 0800 and requested that the airplane be fueled. The airplane was pulled from its heated hangar into heavy snowfall and fueled at 0917. As the airplane sat outside in the heavy snowfall, a measurable amount of wet slushy snow accumulated on the airplane. The Fixed Base Operator manager suggested to the pilot that the airplane be deiced, but he declined. The airplane was then pulled out to the taxiway in an effort to prevent it from becoming stuck in the snow. At 0939, approximately 22 minutes after the airplane was pulled out if its hangar, the pilot departed with a visibility of 3/4 of a mile in snow and with a 4-knot direct tailwind. The pilot then made a right turn and announced that he was heading to his first waypoint. The airplane continued into an ever tightening right turn until it impacted the ground while in an inverted position about one mile north-northwest of the runway. An examination of the airplane’s wreckage revealed no anomalies with either the engine or airframe that would have contributed to the loss of control. The airplane’s Pilot Operating Handbook and Airplane Flight Manual contained the following limitation: "The aircraft must be clear of all deposits of snow, ice and frost adhering to the lifting surfaces immediately prior to takeoff."

Radar data showed the airplane proceeding outbound for the procedure turn. The pilot reported that they were having trouble extending the landing gear and stated, " ... we’re trying to turn back in and do our gear here all at the same time." Shortly thereafter, the other pilot reported that they had extended the gear and had "three good, three green lights, so we’re hoping the gear is down." The pilot also said, "we are now turned inbound." She was told to contact Unicom. This was the last recorded radio transmission from the flight. The Unicom operator said that she heard the pilot say that they were "coming in." Radar data indicated the airplane crossed the localizer at almost a 90-degree angle and continued turning right until it started to intercept the localizer. The data then indicated that the airplane made a left turn away from the localizer that continued and terminated near the accident site. The turn was captured by six plots. The first plot showed the airplane had descended from 9,400 feet to 9,200 feet and its ground speed had increased from 85 knots to 152 knots. The second plot showed the altitude had increased to 9,700 feet and ground speed had decreased to 132 knots. The third plot showed the altitude had increased further to 10,200 feet and ground speed had dropped to 76 knots. The fourth plot showed the airplane had made almost a 180-degree turn and was at 8,900 feet and at a ground speed of 120 knots. The fifth plot showed the airplane was at 8,700 feet and 20 knots. The sixth and final plot showed the airplane at 8,400 feet and 38 knots. An examination of the airplane showed both wing flap jackscrews retracted and the landing gear actuators extended. The landing gear control switch was in the down position and the emergency gear extension knob was pulled out to full travel. Reduced visibility and clouds were in the vicinity of the airport at the time of the accident.

The Part 135 cargo flight was approaching its destination on an IFR flight plan. The pilot had requested the ILS-DME approach to runway 10, but 2 minutes later, he changed his request to the VOR-B approach to runway 28. ARTCC cleared him for the approach to the non-towered airport. The pilot contacted the airport's Unicom, and requested that the ramp personnel be standing by with fuel and oxygen. The airplane was found 5.8 nm from the approach end of runway 28, at 7,900 feet. The approach minimums for the VOR-B was 7,900 feet, which the pilot could descend to at 8.7 nm. The VOR was located 285 degrees at 13.6 nm from the accident site, and the ILS-DME transmitter was located 285 degrees at 5.6 nm from the accident site. The airplane was equipped with a single DME display head, and it had a Nav 1/Nav 2 selector switch.

A maintenance supervisor and two pilots noted that the left engine did not respond normally while being started. Aft starting, the pilot taxied to runway 10 for an IFR departure. Since the taxiway did not extend to the end of the runway, the pilot of another aircraft waited on the taxiway, just short of the runway, approximately 2,967 feet from the end. He observed smoke coming from the left engine of the MU-2 and reported this info on the unicom frequency. He reported that the MU-2 continued and rotated for takeoff approximately 200 to 250 yards east of his position. Reportedly, the aircraft climbed to approximately 300-400 feet afl, then turned left toward higher terrain. After turning, it enter what two witnesses described as a VMC roll, then crashed and burned. An examination of the airframe revealed no preimpact mechanical failures. A teardown of the left engine revealed that a turbine bearing, pn 3101092-1, had been misaligned and subsequently began to fail, damaging the 2nd and 3rd stages of the turbine section. The airport elev was 6,597 feet. The computed takeoff roll was 1,620 feet and the computed accelerate stop distance was 3,100 feet. The landing gear and selector found in down position. The aircraft was destroyed and all six occupants were killed.

The aircraft was 20 feet agl during landing when the crew heard a propeller go into beta mode and the aircraft yawed to the right. The pilot lost control of the aircraft and it collided with a snow bank which separated the wings from the fuselage. Impact damage made it impossible to tell why the propeller went into beta mode.

The pilot, sole on board, was completing a corporate flight from Denver to Hayden-Yampa Valley Airfield, Colorado. On approach, he encountered poor weather conditions due to low ceiling and fog. At an altitude of 7,200 feet, the twin engine airplane struck the slope of a mountain and crashed in flames 3,3 nm from the runway 10 threshold. The aircraft was destroyed and the pilot was killed.