Flight History
On August 6, 2016, about 0820 central daylight time, an experimental amateur-built Wilson Bugatti-DeMonge 100P airplane, N110PX, impacted terrain shortly after takeoff from runway 35L at the Clinton-Sherman Airport, near Burns Flat, Oklahoma. The airplane was registered to Le Reve Bleu LLC and operated by the pilot as a 14 Code of Federal Regulations Part 91 test flight. Day visual meteorological conditions prevailed, and no flight plan was filed. The local flight was originating from CSM at the time of the accident.
A witness reported that the airplane lifted off the runway, then banked right and left during initial climb. The left bank increased, the airplane descended nose down, and impacted terrain inverted. Review of a chase helicopter's video was consistent with the witness statements.
Pilot Information
The 66-year-old pilot held an FAA airline transport pilot certificate with single-engine land, multi-engine land, and instrument airplane ratings. He held a second-class FAA medical certificate issued on May 12, 2016, with limitations: "Must wear corrective lenses. Not valid for any class after 05/31/2017." The pilot reported 10,700 hours of total flight time and 25 hours in the previous six months.
Aircraft Information
N110PX was an experimental amateur-built, twin-engine, single-seat, tailwheel monoplane. It was a replica of the Bugatti-DeMonge 100P, a 1930s air racer never flown. The accident airplane was the first and only replica produced. Powered by two Suzuki Hayabusa reciprocating, clutched motorcycle engines mounted in tandem aft of the cockpit, driving two coaxial contra-rotating Hercules fixed-pitch wooden propellers. Throttle control was via two levers on the left side of the cockpit; clutch engagement via two levers on the right side. Maximum gross weight: 2,939 lb; empty weight: 2,470 lb. The airplane received its FAA Special Airworthiness Certificate on August 4, 2015.
Meteorological Information
At 0753, weather at CSM was wind 040° at 9 knots, visibility 10 statute miles, sky clear, temperature 23°C, dew point 21°C, altimeter 30.06 inches of mercury.
Wreckage and Impact
The wreckage was found about 1,900 ft and 335° from the departure threshold of runway 35L, inverted on an approximate 330° heading. A ground depression was observed about 110° and 23 ft from the wreckage, containing clear plastic and blue color transfer. The airplane forward of the empennage was discolored, deformed, and charred; the rudder skin was consumed by fire. Splintered propeller blade fragments were found around the wreckage. Control continuity for elevators and ailerons could not be established due to fire damage. No preimpact anomalies were detected in the propulsion drivetrain.
Additional Information
Examination of terrain from the accident site to one quarter mile north revealed a suitable field for emergency landing.
Medical and Pathological Information
An autopsy listed multiple blunt force injuries as the cause of death. Toxicological samples showed ethanol, n-butanol, and propanol, noted by CAMI as possibly from postmortem putrefaction.
Fire
Chase helicopter video showed no inflight fire; fire started after ground impact.
Tests and Research
GoPro cameras from the wreckage were examined. Five of six microSD cards contained retrievable video data for the entire flight; one contained data for a portion. The video showed preflight activities consistent with known procedures. During takeoff, the pilot added power, the airplane became airborne, and the pilot selected gear up. Engine and gearbox gauge indications were in green ranges. The video showed the left/forward engine rpm increasing without apparent throttle input; the pilot later reduced its throttle. The airplane entered uncommanded rolls, and airspeed decayed below stall speed (70 knots). The performance study indicated the sequence was consistent with an aerodynamic stall. The airplane reached a maximum altitude of about 80-100 ft above ground level.