ERA21LA071 · Anthony Mattioli AR-1

The pilot was maneuvering the gyroplane for about 1.5 hours prior to the accident and remained below 1,200 ft mean sea level (msl). The final 2 minutes of automatic dependent surveillance broadcast data showed the gyroplane descending from 950 ft msl and 725 ft msl and the groundspeed increasing from 58 knots to 76 knots The gyroplane was located the morning after the accident in a heavily wooded area about 1 nautical mile from the last data point. Postaccident examination of the airframe revealed that the main rotor blades exhibited chordwise scratching. There were no anomalies with the airframe that would have precluded normal operation prior to the accident. One of the three propeller blades was impact separated from about midspan. The other two blades were undamaged and did not display chordwise scratching. Both the left and right carburetor float bowls contained fuel. The left carburetor float bowl was free of water and contamination. The right carburetor float bowl contained water and a crusty substance. Fuel in the fuel tank sump did not contain any water. The engine was started and run to full power using the ignition system and remaining fuel in the fuel tank, with no anomalies noted. The engine turbo control unit was downloaded and revealed that in the final minute of recorded data, the engine power decreased from 4,804 rpm to 418 rpm and the throttle position went to from 48% to 92%. The final data indicated that the engine power was at 1113 rpm and the throttle position was at 92%. The data suggest that with the throttle position at a higher power setting, while the engine rpm was low, there was at least a partial loss of engine power. In addition to the reduction in rpm, over the final three data points, the airbox temperature dropped, which was another possible indicator of a loss of engine power. Although it could not be determined how the contaminates got into the fuel system, it is likely that the contamination resulted in a loss of engine power as indicated on the data extracted from the turbo control unit since the engine ran without any anomalies after the contamination was drained. Given all available information, it is likely the pilot was attempting to make a forced landing as a result of the loss of engine power, as suggested by the flight track data showing a decrease in altitude during the final moments of the accident flight. Furthermore, the main rotor blades exhibited chordwise scratching, which indicated the main rotor was turning on impact and the propeller did not exhibit chordwise scratching, likely due to the loss of engine power. However, with minimal places to make a forced landing in a heavily wooded state forest, it’s possible the pilot was unable to locate an area to make a forced landing safely.

Verbatim NTSB analysis and probable cause from the NTSB dataset