Amateur-built M24 ORION PLUS N1777W accident near Dauphin Island, Alabama

Probable cause

A partial loss of engine power due to a loss of combustion in the No. 4 cylinder for undetermined reasons.

NTSB analysis

The pilot of the gyroplane reported several lane warnings during the flight, which indicated possible disruptions to the fuel/ignition timing by the engine’s digital engine control unit (ECU). The ECU was comprised of two modules that worked in sync with each other to monitor numerous sensors throughout the engine. Although the pilot tried to reset the lane warning several times, the engine lost partial power. The pilot was unable to maintain altitude and made a forced landing in tall grass, during which the gyroplane rolled over and substantial damage.

A postaccident examination and test run of the engine revealed no obvious mechanical malfunctions or failures that would have contributed to the accident. Data downloaded from the engine’s digital ECU and an electronic flight information system (EFIS) revealed that, at the time of the partial loss of engine power, the exhaust gas temperature (EGT) reading for the No. 4 cylinder dropped to levels indicating that combustion was no longer occurring within the cylinder. The loss of combustion in the No. 4 cylinder likely resulted in the partial power loss of the engine.

The cause of the loss of combustion in the No. 4 cylinder could not be determined with the available engine ECU and EFIS data. Along with the engine data, the fact that the engine ran after the accident indicated there was likely an intermittent issue with the fuel/air delivery or the ignition to the No. 4 cylinder that could not be duplicated.

Text from the NTSB. Open the NTSB docket for ERA23LA251 for the full record.