ERA23LA251

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.

On May 30, 2023, at 1101 central daylight time, an amateur-built Magniflight M24 Orion Plus gyroplane, N1777W, was involved in an accident near Dauphin Island, Alabama. The pilot and the passenger were not injured. The flight was conducted as a 14 Code of Federal Regulations Part 91 personal flight. The pilot, who was also the owner and builder of the gyroplane, had been practicing touch-and-go landings. After the eighteenth touch-and-go, while climbing out, a lane warning light came on in the cockpit. The pilot stated that he reset the warning light via a toggle switch with no disruption to the engine. As they continued to climb out, the warning light came back on and the engine lost partial power. The pilot reset the toggle switch again, but full engine power did not return. Unable to maintain altitude, the pilot made a forced landing in tall grass. The pilot said the tall grass made it hard for him to judge his height above the ground. The gyroplane landed on “muddy, wet soil” and rolled over, resulting in substantial damage to the airframe. The engine and propeller system sustained minor damage. The engine was examined and test-run on the airframe using the gyroplane’s existing fuel system. Examination of the reduction gearbox and the lubrication/cooling/exhaust and turbocharger systems revealed no mechanical anomalies. The air filter was absent of debris. The fuel pumps functioned normally when electrical power was applied, and a small amount of debris was observed in the gascolator filter. Fuel in the gascolator was absent of debris and water. The engine was test-run in both the turbocharged and normally aspirated state; it started normally and ran without interruption during each run. The engine examination revealed that a required crossover feed line with a metered orifice, as specified by the engine installation manual, was not installed. In addition, the spark plugs, which had been installed at the last annual inspection, were not approved to be used on this engine per Rotax Service Letter, “Non-approved modifications or use of ROTAX® unapproved engine components or accessories for ROTAX® Aircraft Engines.” However, during the engine run, these items did not affect engine operation and no mechanical malfunctions or failures were identified that would have precluded normal operation of the engine. The engine’s last annual examination was completed on March 31, 2023, at a total engine time of 353.6 hours. The engine had accrued a total of 380.8 hours at the time of the accident. The engine was equipped with a digital ECU. Per Rotech,who represented the engine manufacturer, the ECU was comprised of two modules, Lane A and Lane B. These modules work in sync with each other and monitor numerous sensors throughout the engine. Both lanes rely on sensor data to maximize engine efficiency and performance, including precise calculation of fuel/air mixture delivery and ignition timing to each cylinder. If the ECU senses a disruption to thisfuel/ignition timing, it will issue a lane warning to the pilot. A review of the ECU data revealed that the pilot did not conduct a “Lane” check before departure, and only Lane B was active for the first 24 minutes of the 1.3-hour Flight, until Lane A was turned on. This resulted in several engine parameters, including throttle position and EGT data, not being recorded for the beginning of the flight since these parameters are only recorded on Lane A. Per Rotech, the pilot should conduct a “Lane” test prior to flight to ensure both lanes are turned on and synchronizing in the ECU. ECU data for the accident flight revealed that before the partial loss of engine power, its speed was 5,380 rpm, with the throttle position set to 100%. About 7 seconds later, a lane failure was triggered, causing both Lane A and Lane B warning lights to illuminate in the cockpit. The pilot reset the Lane B toggle switch to clear the failure warning, and the gyroplane continued to climb. During this time, the engine speed and throttle position remained stable, with the throttle set at 92% and the engine speed at 4,558 rpm. About 3 minutes after the lane warnings, the engine rpm dropped to 3,672 rpm with no movement of the throttle by the pilot. The pilot reset the Lane B toggle switch again and moved the throttle between 100% and 28%. During these throttle adjustments, the engine speed responded to the throttle input commands, indicating that the engine was still partially responsive. However, when the throttle was returned to 100%, the engine speed only reached a maximum of 4,210 rpm. This represented about a 22% reduction in engine power as compared to when the throttle was 100% earlier in the flight. The pilot reset the Lane B toggle switch again; however, engine power did not recover. At the time of the loss of engine power, the EGT readings for the No. 4 cylinder dropped from 1458°C to 201°C, consistent with combustion no longer occurring within the cylinder. At the same time, the ECU-calculated fuel injection mass for the No. 4 cylinder dropped significantly on both ECU lanes. According to Rotech, the ECU calculated value does not necessarily mean there is no fuel delivery to the cylinder; it could indicate an ECU injector test mode, or an injector or combustion fault that is affecting the No. 4 cylinder. The ECU data also revealed that the No. 3 cylinder was operating, but the EGT probe had not been working for the last 184 hours before the accident. The airplane was also equipped with a Dynon EFIS that recorded some engine data. The data was consistent with the ECU data in that the No. 3 cylinder was functional; however, its EGT probe was not working properly. The No. 4 cylinder stopped combusting, as evidenced by a significant temperature drop that never recovered, even with throttle inputs, resulting in a loss of rpm. Fuel pressure and fuel flow were consistent throughout the partial loss of engine power. The ECU recorded a total of 261 warnings, 221 faults,and 140 failures over the life of the engine. According to Rotech, some of these faults (Lane Communication CAM Pulse Failed) were indicative of synchronization issues with the ECU that could have contributed to fuel injection and ignition timing and recurring electrical issues. Furthermore, an injector and ignition driver calibration fault identified as "Calibration Too Low" was triggered near the accident period, suggesting possible deficiencies in maintaining optimal fuel injection and ignition timing.