Engine Restart Was Unsuccessful, And The Pilot Initiated A Forced Landing

Location: Montrose, MO Accident Number: CEN20LA412
Date & Time: 09/20/2020, 1145 CDT Registration: N210WP
Aircraft: ZENITH CH 750 Injuries: 1 None
Flight Conducted Under: Part 91: General Aviation - Personal

On September 20, 2020, about 1145 central daylight time, a William Prosch Zenith 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 en route 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's left wing leading edge was crushed, and the rudder was bent.

Postaccident examination of the airplane revealed 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 back up ECUs, displayed arching 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 buss 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 engine manufacturer has a service bulletin that recommends an ECU wiring upgrade. The upgrade removes the ECU select switch in order to operate on a single computer only. The service bulletin had not been completed on the accident experimental airplane, nor was it required to be completed.

FMI: www.ntsb.gov