History of Flight
On October 4, 2011, about 1315 mountain daylight time, an experimental Vaughn Pulsar airplane, N91BV, impacted terrain about one-half mile south of the departure end of Runway 16 at South Valley Regional Airport, West Jordan, Utah. Both the certified flight instructor and his passenger received fatal injuries. The airplane, which had been purchased earlier that day by the passenger, sustained substantial damage. The flight was personal under 14 CFR Part 91, departing in visual meteorological conditions for Nephi, Utah. No flight plan was filed.
The previous owner stated that the potential buyer had visited about two weeks earlier. The engine was started and taxied, running well. The buyer said he would arrange for a flight instructor to pick up the airplane. On the accident day, the seller noticed the instructor appeared heavier than stated and advised them about gross weight limits, suggesting no additional fuel beyond the 9 gallons already onboard. He gave the instructor a weight and balance sheet. After handing over keys and paperwork, the seller left. No record of additional fuel being added was found.
Witnesses saw the airplane taxi to the northern end of Runway 16 about 5 minutes before takeoff, stopping in the run-up area. The pilot then started the takeoff roll. A flight instructor who watched from about halfway down the runway reported that the airplane had already lifted off, engine sounding at full power, just above the runway in ground effect. It was climbing barely and porpoising repeatedly. As it neared the departure end, another instructor radioed, "Experimental aircraft on departure, are you having technical difficulties?" The pilot responded, "No, it's just a weak aircraft." The porpoising continued until about one-half mile off the runway at about 75 feet agl, then the airplane entered a shallow right turn, banked to near 90 degrees, nose dropped about 45 degrees below horizon, and it descended rapidly into terrain.
Personnel Information
The pilot was a 28-year-old male holding commercial pilot and certified flight instructor certificates for single-engine and multi-engine land airplanes, with an instrument rating. He had about 2,100 flight hours. It is unknown if he had flight time in the accident make and model.
Aircraft Information
The airplane was a 1992 kit-built experimental Vaughn Pulsar with about 250 total hours. It had a 65-horsepower Rotax 582 Mod 90 engine and a fixed-pitch composite propeller. Maximum allowable gross weight was originally 870 pounds, with an undated notation increasing it to 1,000 pounds per Aero Designs. A weight and balance calculation from a prior flight listed actual ramp weight of 963 pounds and max gross of 1,000 pounds.
Meteorological Information
METAR from Salt Lake City International Airport about 10 miles north, recorded at 1253, indicated wind from 200° at 14 knots gusting to 19 knots, 10 miles visibility, few clouds at 6,000 feet, scattered towering cumulus at 9,000 feet, temperature 23°C, dew point 8°C, altimeter 29.86 inHg. A special METAR at 1338, about 25 minutes post-accident, showed wind from 200°-270° at 9 knots gusting to 21 knots, thunderstorms with light rain. The AWOS at the airport reported wind from 150° at 12 knots gusting to 18 knots, 10 miles visibility, scattered clouds at 10,000 feet, temperature 23°C, dew point 7°C, altimeter 29.88 inHg. A ground witness noted small rain cells moving through earlier but no cell over the airport at accident time; wind was nearly steady about 15 knots down the runway. Density altitude at takeoff was calculated to be 6,790 feet.
Communications
The only known radio transmission from the accident airplane was the pilot's response to a query about technical difficulties: "No, it's just a weak aircraft." No further transmissions.
Wreckage and Impact
The airplane struck flat grassy terrain in a soccer field complex about one-half mile south-southeast of the departure end. Initial impact scar cut through grass about 6 inches deep, 1 foot wide, 3 feet long. A 20-foot-wide swath of debris extended west. The main wreckage came to rest about 40 feet west. Wings were broken apart; cabin separated; both occupants were ejected. The fuselage from forward of baggage area to empennage remained structurally intact except for a vertical skin crack. Left horizontal stabilizer, elevator, vertical stabilizer and rudder were undamaged and attached; right horizontal stabilizer and elevator were torn off. All airframe parts were present.
Post-recovery examination found flight control continuity from aft cockpit to rudder and left elevator, and to right elevator actuating system. Fuel selector was on; fuel filter was uncontaminated. Induction air filter was crushed but clean. Propeller was attached; blades showed rearward crushing and gouging. Engine teardown revealed gearbox partially separated and damaged. Ignition wires had chafing, but preimpact condition undetermined. Cylinders, pistons, connecting rods, bearings had no anomalies. Exhaust system was modified from original, which could negatively affect power output. Crankshaft seal was leaking, potentially reducing performance. All four spark plugs were heavily sooted, consistent with abnormally rich mixture. Both carburetors had 180 main jets (stock 165) and jet needles incorrectly placed, resulting in much richer mixture, significantly reducing power at higher altitudes. Carburetors had been rebuilt on October 15, 2008.
Medical and Pathological Information
Autopsy determined cause of death as blunt force injuries to head, neck, and trunk. Toxicology on pilot was negative for ethanol and screened drugs except for low levels of ephedrine in urine and muscle tissue, and lidocaine (concentration not reported). Carbon monoxide and cyanide tests were not performed.
Additional Information
Takeoff gross weight was calculated using autopsy weights: instructor 256 pounds, passenger 194 pounds (total 450 pounds), plus 55 pounds fuel (9 gallons at 50:1 oil mix), and empty weight 526 pounds per latest weight and balance, totaling 1,031 pounds—31 pounds over maximum allowable gross weight of 1,000 pounds.