WPR26LA072 · Zenith 750 Super Duty

The pilot was returning to the airport while conducting a phase 1 test flight in an experimental airplane when he detected a burning odor. He scanned the engine instruments which all showed normal indications. Shortly after, about 4 miles from his home airport, the engine shut down. He reported his position and intentions on the local radio frequency and initiated a forced landing to a down sloping field. During the landing roll the airplane impacted terrain, sustaining substantial damage to the fuselage and wings. The pilot also reported that after he exited the airplane, he didn’t see any oil or water dripping from the cowling or oil spray on the windshield. At the time of the accident the airplane had accrued 16 hours of operation. The FAA conducted a postaccident examination of the experimental airframe and engine, which revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. The pilot further reported that he found an odor from one of the engine control unit (ECU) connectors, although a review of the electrical system by the FAA did not reveal any evidence of electrical system damage. The ECU was sent to the engine manufacturer and tested normally with a functioning engine. Based on this information, the reason for the loss of engine power could not be determined.

Verbatim NTSB analysis and probable cause from the NTSB dataset