20160104000289A

On 01/04/2016@1530 near Alpine airpark (46U) a yak 52 was conducting maneuvers that were described by witnesses as aerobatic (loops and rolls). A pilot and a single passenger were onboard. This operation was reported to have been conducted approximately 1.5-2 miles to the north west of the airport. At approximately 1610 the yak 52 departed the area where operations were being conducted made a radio call to another aircraft approaching the airport for landing. The aircraft contacted was on 3 mile final for a landing at the airport. The yak 52 notified the pilot of the yellow husky of his intent to form up on him and to do a low level pass at the airport by transmitting ?yellow husky better watch out?. This statement was reported as a common phrase used between these two pilots to indicate intention to perform a low pass of the airport. It was also reported this was a common maneuver for these two pilots to perform together. The pilot of the yellow husky leveled out and applied power in preparation for the maneuver. It was reported this aircraft was appx 300? To 400? AGL at the time. The flat ground surrounding the airport and lake in the area was completely covered by snow. The weather was clear and the only contrast available for terrain position would have been the runway and the surrounding mountains. The yak 52 now maneuvering to line up on the other aircraft would have to have gone around to the east and turned back toward the south headed toward the airport for a low pass formation on the other aircraft. During this maneuver at approximately 1630 the yak 52 struck the ground left wing first at a high rate of speed. There were ground markings noted at the initial impact point that are consistent with this conclusion(pieces of the left wing tip cap and pitot tube were also recovered at this location, the pitot tube was buried in the ground 1.5 feet). Upon inspection of the debris field it was noted the heading or path of the field was at 122 degrees and 183 yards long. The prop hub was recovered still connected to a large piece of the reduction gear housing but separated from the engine assy. It was noted two of the propellers were broken off at the root from the hub and any pieces of the propellers recovered were shattered and splintered. The left hand wing had broken off at the spar, yielding of the lower l/h wing lug connection on the spar was bent aft ward in relation to the aircraft. Wiring and cable assemblies inspected at broken points showed sign consistent with breakage due to overload (broom-strawed ends). Structural pieces recovered from the accident scene all showed signs of ductile failure due to stretch, bending and/or torque overload. The accident scene was approx. 1.8 miles north west of the airport (309.89 degrees from the end of the run way). All persons onboard were killed. Pilots logbooks at the time of this report were unavailable. This report will be ammended as further information becomes available.