Amateur-built TM-1 N151WR accident near Santa Clarita, California

Probable cause

Engine detonation that resulted in material deformation of the crankcase and led to engine failure and restricted cockpit visibility.

NTSB analysis

The pilot departed for flight in an amateur-built experimental airplane. A few minutes after takeoff, the pilot made a distress call to the airport tower controller stating a loss of engine power and a cockpit visibility issue. A witness observed the airplane maneuvering at a low altitude with smoke trailing from the airplane. Subsequently, the airplane struck a tree and impacted terrain in a grassy field located in the median of an interstate’s off-ramp, destroying the airplane.

Postaccident examination of the engine revealed damage that was consistent with detonation. One cylinder had material deformation that had burnt through the crankcase. Other cylinders had varying degrees of material deformation on their piston faces and cylinder heads, and the piston faces, and cylinder heads were absent of any carbon buildup. During the forced landing, the hole in the crankcase would have leaked coolant and oil, creating smoke and limiting the visibility from the cockpit, which likely would have prevented the pilot from seeing and avoiding the tree. The specific reason for the detonation could not be determined.

Text from the NTSB. Open the NTSB docket for WPR20FA057 for the full record.