CEN23LA250

The pilot purchased the airplane on the day of the accident and was planning to fly it to another airport. On the morning of the accident, a mechanic completed an annual inspection on the airplane. During the preflight inspection and the runup, no anomalies were noticed by the pilot. During the initial takeoff climb, the pilot noticed a decrease in the engine rpm. The pilot was unable to maintain altitude, and he was unable to identify what caused the partial loss of engine power. Shortly thereafter, the engine sustained a total loss of engine power, and the pilot performed a forced landing. Upon touchdown to a residential road, the airplane impacted a tree and an unoccupied motor vehicle. The airplane came to rest upright in the rear of another unoccupied motor vehicle. The airplane sustained substantial damage to the right wing and the fuselage. Postaccident examination of the airplane revealed significant wear of the locking mechanism on the manual fuel primer pump: only a narrow portion of the retaining lip was left to engage with the retaining pin. It is likely that a slight movement or vibration caused the retaining pin to move around the small piece of retaining lip that remained, resulting in the fuel primer pump becoming unlocked and extending. The spark plugs were found in a carbon fouled condition, consistent with an overly rich mixture. The fuel primer pump position and the condition of the spark plugs indicate that the total loss of engine power was likely due to an overly rich mixture resulting from excess fuel being pulled through the fuel pump primer and into the engine’s intake system when power was applied.

On June 21, 2023, about 1330 central daylight time, a Champion 7EC airplane, N80461, sustained substantial damage when it was involved in an accident near Waunakee, Wisconsin. The pilot and the passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot purchased the airplane earlier on the day of the accident and was planning to fly it to the Brennand Airport (79C), Neenah, Wisconsin. On the morning of the accident, a mechanic completed an annual inspection on the airplane. Before the departure from the Waunakee Airport (6P3), Waunakee, Wisconsin, the pilot added 10.7 gallons of 100 low-lead fuel. During the preflight inspection and the runup, no anomalies were noticed by the pilot. During the initial climb from runway 9, the pilot noticed a decrease in engine rpm. The pilot was unable to maintain altitude, and he was unable to identify what caused the partial loss of engine power. Shortly thereafter, the engine sustained a total loss of power, and the pilot performed a forced landing. Upon touchdown to a residential road, the airplane impacted a tree and an unoccupied motor vehicle. The airplane came to rest upright in the rear of another unoccupied motor vehicle, and the two occupants were able to egress from the airplane without further incident. There were no injuries to persons on the ground. The airplane sustained substantial damage to the right wing and the fuselage. Postaccident examination of the airplane revealed that the airplane was equipped with a manually operated Kohler fuel primer pump (a piston-type pump). The fuel primer pump (part number K-2406-2 and no serial number listed) was found extended and unlocked, and the fuel primer pump would not lock. After a fuel primer pump is used to prime the engine during the starting sequence, it is supposed to be secured in and locked. Examination of all the spark plugs found them carbon-fouled, consistent with a rich mixture condition. A postaccident materials laboratory examination of the fuel primer pump revealed that the pump’s piston had a cylindrical pin perpendicular to the piston’s axis, which was used to lock the piston in the fully inserted position when not in use. The locking pin was about 0.093” diameter. The locking pin would normally kept captive by a retention lip on the pump housing end cap when the piston was fully inserted and turned either to the left or right. Examination of the end cap revealed that the retention lip on the end cap was worn away around most of its circumference, leaving only a 0.143-inch section of the retaining lip. Champion 7EC fuel system installation drawings #7-796 and #7-10002 (located in the Champion 7EC Operating and Service Manual), show that a Kohler fuel primer pump (part number K-2406-2) is used. However, the Champion 7EC Operating and Service Manual does not list any continued airworthiness guidance for the fuel primer pump. A review of the Federal AviationAdministration (FAA) Aviation Maintenance Technician Handbook - Airframe (FAA-H-8083-31B) found a description of how a manually operated fuel primer pump operates. However, a review of FAA Advisory Circular 43.13-1B Acceptable Methods, Techniques, and Practices – Aircraft Inspection and Repair, found no inspection guidance for manually operated fuel primer pumps. During the investigation, the FAA attempted to contact Kohler multiple times, with no response received. A search conducted by the FAA for any airworthiness information on the fuel primer pump revealed no such documents.