CEN23LA337

The pilot stated that on final approach, with full flaps down and the airplane about 50 ft above ground level (agl), the propeller stopped turning and the engine lost all power. He stated that he added power, but the engine did not respond. The pilot was unable to arrest the descent and the airplane landed hard, which resulted in substantial damage to the fuselage. Postaccident examination of the airframe and engine revealed that the fuel servo idle mixture adjustment was found in a nearly full-lean setting. Although an improperly set idle mixture adjustment could have resulted in a total loss of engine power at a low power setting, the examination was unable to identify the preaccident idle rpm and idle mixture settings and was therefore unable to determine if the full-lean setting resulted in the loss of engine power while on final approach. Examination of the rest of the engine, including the ignition and fuel injection systems, revealed no additional defects or abnormalities.

On July 30, 2023, about 1655 central daylight time, a Cub Crafters CCX-2000 Carbon Cub airplane, N967DT, was substantially damaged when it was involved in an accident near Winsted, Minnesota. The pilot was uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that before departure, he ensured the airplane was fueled to capacity, and he checked all three fuel drain ports for water and contamination, with none noted. The pilot departed from Crystal Airport (MIC), Minneapolis, Minnesota, and flew toward Winsted Municipal Airport (10D), Winsted, Minnesota, about 31 nautical miles west of MIC. After practicing slow flight and a series of stalls, the pilot decided to land at 10D. The pilot stated that the airplane was performing well, and he observed no anomalies during the flight until final approach, when the engine lost all power about 50 ft agl. The pilot reported that his first indication of power loss was when the propeller stopped rotating. He further stated that he was close to the ground and did not attempt an engine restart or conduct the emergency checklist. The pilot reported he then applied full throttle, pushed the stick forward to unload the wings and prevent a stall, then quickly pulled the stick aft to slow the descent rate. The pilot was unable to arrest the descent, and the airplane landed hard on the turf runway, which resulted in substantial damage to the fuselage. Postaccident examination revealed that the fuselage was fractured and dented in several locations, and the trailing edge of the right aileron was damaged. The fuel tank and drain sumps contained aviation fuel that was clean and free of debris and water. The engine reservoir contained oil, and no debris or metallic material was present in the oil filter. The electronic ignition system could not be tested. All spark plugs appeared in normal condition, with moderate carbon fouling and no electrode damage or oil fouling. The air filter was partially soiled. The fuel injectors and flow divider were unremarkable. The fuel servo was unremarkable except for the idle mixture adjustment, which was found in a nearly full-lean setting. Manual rotation of the engine by the propeller produced thumb compression in each cylinder and established accessory gear and valvetrain continuity. Further examination was completed by an independent mechanic after recovery of the airplane. At that time, the mechanic removed 30 gallons of fuel from the airplane. The ignition system wiring was unremarkable and the ignition modules were tested by the manufacturer with satisfactory results. The fuel injection system was also sent to the manufacturer for inspection, with no defects or abnormalities found. The independent mechanic removed each cylinder from the engine and internally inspected the engine and found it to be unremarkable. A download of data from the onboard Garmin G3X electronic flight instrument system recovered 805 flightlog files, including the accident flight of about 1 hour 11 minutes. The data showed that the flight departed MIC and proceeded uneventfully until the final moments of the approach to 10D. At 1654:33, about one minute before the total power loss, engine parameters started showing a progressive decline in power output. At that time, the engine was producing 23% power at 1,820 rpm, with the airplane at a GPS altitude of 1,806 ft and an indicated airspeed of 57 kts. Within four seconds, engine power decreased to 21% at 1,500 rpm, and power continued to decline to 12% at 970 rpm. Over the next 40 seconds, engine power and speed continued to fall alongside decreasing cylinder head and exhaust gas temperatures. At 1655:28, the engine speed fell to 150 rpm, with a corresponding increase in manifold pressure to 26 inches of mercury, consistent with an engine shutdown. At that time, the GPS altitude was 1,064 ft and the indicated airspeed was 45 kts. The ignition back-up and left and right ignition off messages were briefly active only before takeoff and did not activate while the airplane was airborne. The integrated battery back-up system in use message was never active during the accident flight. The pilot provided investigators with a video of the accident from a camera mounted in the cockpit. The video began with the airplane flying on a north-northeasterly heading, about to turn left onto the downwind leg to land at 10D. The pilot communicated his intent to land on runway 9 and back taxi. The pilot then made several inputs to reduce engine power and to turn onto left base. The final portion of the video continued with the airplane on final approach when the engine stopped running about 45 ft agl. Crew alerting system messages activated shortly thereafter, alerting the pilot of “AMPS” and “OIL PRESS.” The pilot then applied full throttle and abruptly pulled the control stick aft. The airplane landed hard, the landing gear collapsed, and the airplane ground looped toward the left during the rollout. The video ended shortly thereafter.