CEN24LA203

The pilot reported that, during the initial climb, the engine lost partial power. He flew a left traffic pattern to return to land; during the forced landing, the airplane landed short of the runway and left of the runway centerline. The nose landing gear assembly separated from the airplane and the fuselage sustained substantial damage. Examination of the airframe, engine, and fuel systems did not reveal any preimpact malfunctions or failures that would have precluded normal operation. Data downloaded from the engine control unit (ECU) revealed engine rpm fluctuations about 2 minutes after takeoff and again about 3 minutes after takeoff, but rpm values recovered, and all other parameters remained normal. The reason for the reported loss of power and the engine rpm fluctuations logged in the data could not be determined.

On May 25, 2024, about 0645 central daylight time, an experimental Pulsar Super 100 airplane, N912GR, was substantially damaged when it was involved in an accident near Rochelle, Illinois. The pilot was not injured. The airplane was operated under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. The pilot stated that, during the initial climb, the engine began to lose partial power. About 800 ft above ground level, he turned onto the left crosswind leg of the traffic pattern with the intent of returning to land. Shortly after turning onto final approach, the airplane contacted the ground about 15 ft before the runway and 25 ft left of the runway centerline. The airplane impacted two runway lights, then skidded about 100 ft down the left side of the runway. The nose landing gear assembly separated from the airplane and the fuselage sustained substantial damage. The airframe and flight controls were examined after the accident and no anomalies were found. The responding FAA inspector completed an initial examination of the engine and found that the spark plug electrodes were dark grey in color. Compression and suction were attained on all four cylinders when the crankshaft was rotated by hand, and internal continuity was confirmed. None of the engine components examined exhibited any anomalies. Due to the damage, the inspector was unable to functionally test the ECU and associated sensors. About 12 gallons of fuel was recovered from the airplane. No water was present in the fuel when tested with water-finding paste. The fuel tank vents were clear of debris. Fuel system continuity from the fuel tanks to the engine was established using low pressure air. Both electric fuel pumps were functionally tested with no anomalies noted. The memory card from the Electronic Flight Instrument System (EFIS) was downloaded but contained no data relevant to the accident flight. The nonvolatile data from the ECU was downloaded and functionally tested by the engine manufacturer, ULPower. The ECU stored engine data from the previous 20 minutes (or 20 sessions). A session (or log) starts to record when the rpm of the engine is above 71.59. Examination of the ECU revealed that the engine was started and warmed up. Coil 2 was then switched off three times, consistent with a preflight check. About 5.5 minutes after engine start, the throttle position increased to wide open throttle, and the engine rpm increased to maximum, consistent with takeoff power. About one minute later, the throttle was set to a constant parameter, and the rpm dropped accordingly, consistent with a cruise power setting. About 7 minutes and 20 seconds after the recording began, and again at 8 minutes 10 seconds, a significant drop in rpm was noted; however, the rpm recovered and all other parameters remained constant. The engine stopped at 8 minutes, 25 seconds. During the recorded data, the engine check light was not activated, indicating that there were nosensor failures.