History of Flight
On September 11, 2013, about 1155 mountain daylight time, a single-engine experimental Kamtz Vans RV-7A, registration N820RV, experienced a loss of power and departed controlled flight while the pilot was maneuvering in the traffic pattern at Jackson Hole Airport, Jackson Hole, Wyoming. The private pilot and passenger sustained fatal injuries. The airplane was registered to and operated by the pilot under 14 Code of Federal Regulations Part 91. The personal flight originated from Jackson Hole with a planned destination of Fort Collins-Loveland Municipal Airport, Colorado. Visual meteorological conditions prevailed, and no flight plan was filed.
The pilot had departed Whitefish, Montana earlier and was refueling at Jackson Hole. He intended to fly back to Fort Collins-Loveland, where the airplane was based.
Numerous witnesses observed the airplane maneuvering in the traffic pattern. Most stated that the airplane initially departed from runway 01 and climbed to between 500 and 600 feet above ground level while making a right turn onto the downwind leg. Several witnesses heard abnormal engine sounds described as multiple high revving sequences and sputtering/popping akin to misfiring. The engine appeared to lose partial or total power. The emergency airport siren sounded at that time.
Witnesses further recalled that while the airplane turned from downwind to base leg (a right bank from south to west), a wing dropped and the wings became near perpendicular to the terrain. The airplane then made a rapid descent and impacted terrain in a nose-low attitude.
Recorded radio communications from Jackson Hole Air Traffic Control Facility indicated that shortly after departing runway 01, the pilot stated, "Jackson tower eight-two-zero-romeo-victor, I just lost my… lost power here." The controller cleared the airplane to make a right turn onto base leg and land on runway 01, to which the pilot responded, "eight-two-zero-romeo-victor."
Personnel Information
Federal Aviation Administration records showed the pilot, age 67, held a private pilot certificate with single-engine land and instrument ratings, plus a Repairman Experimental Aircraft certificate. His most recent third-class medical was issued on September 30, 2011, with the limitation that he must wear lenses for distant vision and have glasses for near vision.
According to the pilot's logbook, he had about 1,150 total flight hours, with about 850 in a Van's RV-6A and about 350 in the RV-7. He was a member of the Experimental Aircraft Association and had built the airplane.
Aircraft Information
The Vans RV-7A is an amateur-built experimental kit airplane with two seats, fixed tail-wheel landing gear, and traditional flight controls. The accident airplane, serial number 72751, received a special airworthiness certificate in the experimental category in August 2008.
Maintenance records indicated 287.0 total hours in service. The most recent condition inspection was completed by the pilot on October 3, 2012. Build logs were not provided, so it could not be determined if a stall warning system was installed.
The engine was an experimental Lycoming IOX-360-A41N, equipped with a G3i forced induction supercharger kit mounted on the vertical draft sump. The supercharger was driven from the flywheel via a serpentine belt through the alternator. It utilized a mechanical belt-driven compressor with a pair of four-lobe, high-helix rotors and an integrated vacuum-controlled bypass valve.
Test flight hours were completed in April 2009. The pilot estimated the airplane's stalling speed in landing configuration (Vso) at 52 knots at a weight of 1,740 lbs and CG of 81.79 inches aft of datum.
Just before the accident takeoff, 29 gallons of 100LL Avgas were added to top off both wing tanks.
Meteorological Information
A routine aviation weather report at 1153 recorded skies clear, visibility 10 miles, wind from 30 degrees true (043 magnetic) at 14 knots gusting to 24 knots, temperature 70°F, dew point 41°F, altimeter 30.30 inHg. Minutes before departure, the tower controller reported wind from 040 degrees at 15 knots. After the accident, the controller reported wind from 050 degrees at 16 knots gusting to 26 knots.
With these winds, on the downwind leg the pilot would have encountered a 13-knot tailwind and 8-knot left crosswind. Gusts to 26 knots from 050 would equate to a 20-knot tailwind and 17-knot left crosswind. As the pilot turned to base leg (presumably 280 degrees), the airplane would have a 17-knot tailwind and 20-knot right crosswind.
Wreckage and Impact Information
The accident site was on level terrain of hard dirt and brush, about 3,100 feet from the takeoff threshold of runway 01 on a bearing of about 080 degrees. The first impact point was a crater about five feet long and four feet in diameter containing engine pieces and composite shards. The main wreckage came to rest nose on a heading of about 285 degrees, about five feet from the initial crater. GPS coordinates were approximately 44.590556°N, 110.74333°W, elevation about 6,450 feet msl.
The main wreckage included major airframe components and the engine; the propeller, canopy, and top cowling were found further down the debris field. In the initial crater was an antenna normally on the front underbelly; forward of that were pieces of the exhaust manifold. Two elongated areas of disrupted dirt perpendicular to the main crater were consistent in size and orientation with the wings.
Medical and Pathological Information
An autopsy was performed by Teton Pathology, P.C. The FAA Civil Aeromedical Institute performed toxicological screenings. The report (#201300187001) showed negative for ethanol, but diphenhydramine was detected in liver and urine samples.
Tests and Research
The wings sustained major skin deformation crushing from the leading edge, with bottom leading edge skin folded into an accordion appearance, nearly uniform along the wing length. The crush deformation was consistent with impact at a 45-degree nose-low attitude.
The engine was disassembled. External examination revealed crush damage to the bottom crankcase, mostly to the oil sump. Spark plugs showed no mechanical damage; electrodes exhibited normal dark grey coloration except bottom #2 plug with oily residue. Ignition harnesses were attached; both magnetos produced spark when rotated. Cylinders showed no evidence of foreign object ingestion or detonation. Valves were intact, and combustion deposits were similar across cylinders.
The oil filter had "6-18-13" indicating last oil change date. The filter was cut open and showed no particles. Oil pump gears moved freely and housing contained oil. No pre-impact lubrication contamination was evident.
The Whirlwind 200RV propeller separated from the engine; blades remained attached at hub. Spinner was folded over hub. One blade was straight with no rotational evidence; the other bent aft with s-bends.
The fuel selector handle pointed to the "LEFT" tank position. The fuel filter was clean. The engine-driven fuel pump diaphragm had a slight tear consistent with impact damage. The fuel system was too fragmented to establish continuity.
The supercharger was disassembled after heating; the butterfly valve was frozen in a partially open position. The inside casing was dyed dark blue from extended exposure to 100LL Avgas. Bearings rotated freely with no anomalies noted.