On June 5, 2022, about 1230 Pacific daylight time, an experimental, amateur-built Super Koala airplane with no registration was substantially damaged when it was involved in an accident near Chelan, Washington. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulation Part 91 personal flight.
According to the pilot, on the day of the accident he ran the airplane’s engine up to full speed three times, lasting about ten minutes each time. He departed from the runway and stayed in the traffic pattern at an altitude of about 2,200 ft mean sea level (msl). During a turn to the crosswind leg, the engine lost total power and the propeller continued to windmill. The pilot verified the throttle was at the maximum power setting and that the ignition switch was on. Shortly after, he initiated a force landing to an off-airport field about 600 ft west of the airpark.
The airplane nosed over and came to rest on a hillside covered in vegetation and rocks. The fuselage and both wings sustained substantial damage. All major components remained attached to the airframe except for a section of the wooden propeller blade.
Figure 1. Airplane immediately after the accident. Photo courtesy of the pilot.
The pilot purchased the airplane about 6 weeks before the accident. He had performed maintenance on the airplane that included overhauling the carburetors, installing a new impulse fuel pump, cleaning out the fuel tank, and replacing the fuel lines. He reported about 3.5 gallons of fuel on board at the beginning of the run ups and about 2 gallons remained in the tank after the accident.
A postaccident examination was conducted. The wings and fuel tank were removed from the airport without approval from the IIC and not made available for examination. Detailed information, such as unusable fuel quantities could not be determined. Examination of the carburetors revealed a small amount of a sticky substance on the brass mount for the main jet and inside the plenum for the main jet; however, the main jet and the pilot jet passages were clean and not blocked. The airframe, engine, electrical, and available fuel system components exhibited no mechanical malfunctions or failures that would have precluded normal operation.
A review of the Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, revealed that environmental conditions conducive to carburetor icing did not exist in the area at the time of the accident.