Stinson 108 N97969 accident near Keshena, Wisconsin

Probable cause

A total loss of engine power during cruise flight for undetermined reasons, which resulted in a forced landing and subsequent impact with trees.

NTSB analysis

The pilot was conducting a personal flight; while in cruise flight, the engine experienced a momentary and substantial loss of rpm. The pilot moved the mixture to the full-rich position, turned on the carburetor heat, and switched to the right fuel tank. The engine recovered power, and the pilot left the carburetor heat on for about 3 minutes and then slowly turned it off. About 2 minutes later, the engine lost all power. The pilot activated the starter, but it did not engage. The pilot chose to execute a forced landing on a road, during which the airplane impacted trees, bounced, and then came to rest inverted on a snow-covered embankment.

Postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The temperature and dewpoint at the time of the accident were not conducive for the formation of carburetor icing. The airplane had an adequate amount of fuel onboard at the time of the accident. Therefore, the reason for the loss of all engine power could not be determined.

Text from the NTSB. Open the NTSB docket for CEN19LA060 for the full record.