NTSB: New Report On Bugatti Crash That Killed Broken Arrow Pilot

The National Transportation Safety Board released a new report on the crash of a replica of the Bugatti 100p aircraft that killed the Broken Arrow pilot who was the driving force behind its construction.

Scotty Wilson, 66, died when the single-seat airplane crashed shortly after takeoff in Burns Flat, Oklahoma on August 6, 2016. It was the airplane's third flight.

8/6/2016 Related Story: Broken Arrow Pilot Killed In Crash Of Bugatti 100p Replica

Wilson led the team that built the replica in Tulsa. It was an exact copy of the Bugatti 100p, the only aircraft ever designed by famed car builder Ettore Bugatti. The original 100P never flew, so the international aviation community was watching the progress of the replica's construction and flight testing.

The 100P is known for its unusual design. Bugatti designed it as a racer in 1938, but with the imminent fall of Paris to the Nazis in 1939, he had it disassembled and hidden on his estate. It has since been restored and is on display at the EAA Airventure Museum in Wisconsin.

It's a small, wooden airplane with two engines, both of which sit behind the cockpit. Each engine drives a two-bladed propeller via drive shafts that pass on either side the pilot to the nose of the airplane. The propellers spin in opposite directions, called contra-rotating, canceling out each other's torque.

The NTSB released its second of three reports on the crash a few days ago. Called the Factual Report, it lays out all of the information assembled by NTSB investigators about the crash. It does not contain the NTSB's official opinion on the cause of the incident; that will be included in the Probable Cause Report which is usually released a few weeks after a Factual Report is published.

Read the Factual Report on the Bugatti 100p crash.

According to the Factual Report, the NTSB obtained video from multiple GoPro cameras installed on the airplane, as well as from a helicopter that was recording the flight. An NTSB aerospace engineer was also witnessing the flight and assisted in the investigation of the cause of the crash.

The NTSB said the plane had just taken off and was 80-100 feet above the ground when the forward engine began to increase its RPMs to near its redline.

The report says the airplane banked left as the RPMs surged on the forward engine. The pilot pulled back the throttle for that engine, the NTSB said, but the airplane then banked right. The NTSB said the airplane was below its stall speed at that point, but the pilot returned it to level flight. It then suddenly banked left, according to the report, and as the pilot tried to return it to level flight, it rolled over on its back, crashed into a field and caught fire. 

The report says video evidence showed a sequence of events consistent with an aerodynamic stall. 

The NTSB says Wilson was an airline-rated pilot who had reported about 10,700 flight hours. 

The crash happened a couple of weeks before the first anniversary of the replica's first flight. On that flight, a problem with its brakes left the plane sitting nose down after it landed. 

On its Facebook page, the group that built the aircraft posted its theory about what happened:

It is clear that there was a loss of power to the forward propeller, this is documented by the GoPro cameras that were mounted in the cockpit and is consistent with the eyewitness accounts. Having analysed the cockpit video, the external video and the wreckage, the only reasonable conclusion is that the power failure in the forward engine drive train was the result of a clutch failure in the forward engine.

The degradation in the power transfer from the engine to the propeller is demonstrated clearly by the engine RPM increasing while the air speed and rate of climb remained steady at first and then degenerated. To be clear, the NTSB did not analyse the engines or their integral clutches, so it is our own team that has drawn this conclusion as the only logical explanation.

The group also asked readers to take a moment to honor and remember Scotty Wilson, the only person to ever fly the Bugatti 100p. 

View the team's Facebook page.