CEN20LA412

The pilot of the experimental, amateur-built airplane was en route to the destination airport when the engine momentarily lost power. The pilot immediately selected the alternate fuel pump and engine control unit (ECU), and the engine regained power. About 5 minutes later, the engine lost total power, and the pilot attempted to restart the engine. The engine restart was unsuccessful, and the pilot performed a forced landing to a field, during which the airplane nosed over and came to rest inverted, resulting in substantial damage to the left wing and rudder. Postaccident examination of the airplane revealed that the main fuse block was discolored and exhibited internal thermal damage. An automotive blade-type fuse that connected to both primary and secondary fuel pumps and primary and backup ECUs displayed arcing signatures and had failed. According to the engine manufacturer, the primary and secondary ECUs should have been wired directly to the main bus and should not have contained a fuse. The improper installation of the airplane’s electrical system resulted in an overloaded electrical system for the installed fuse. After bypassing the failed electrical system, an engine test run was performed. The engine started and operated normally with no mechanical issues noted.

On September 20, 2020, about 1145 central daylight time, an experimental, amateur-built CH 750 airplane, N210WP, was substantially damaged when it was involved in an accident near Montrose, Missouri. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, while enroute to his destination airport, the engine momentarily lost power. He immediately selected the alternate fuel pump and engine control unit (ECU), and the engine regained power. About 5 minutes later, the engine lost total power, and the pilot attempted to restart the engine. The engine restart was unsuccessful, and the pilot initiated a forced landing to a field. During the forced landing, the airplane's landing gear contacted the high vegetation, and the nose impacted terrain. The airplane nosed over and came to rest inverted. The airplane sustained substantial damage to the left wing leading edge and the rudder. Postaccident examination of the airplane revealed that the main fuse block, located behind and under the instrument panel, was discolored and exhibited internal thermal damage. An automotive blade-type fuse, that connected to both primary and secondary fuel pumps and primary and backup ECUs, displayed arcing signatures, and had failed. According to the engine manufacturer, who responded to the accident site, the primary and secondary ECUs should have been wired directly to the main bus and should not have contained a fuse. After bypassing the failed electrical system, an engine test run was performed. The engine started and operated normally with no mechanical issues noted. The accident airplane had not been modified in accordance with an engine manufacturer service bulletin that recommended an ECU wiring upgrade. The upgrade removes the ECU select switch to operate on a single computer only.