Primary finding
Probable cause
The blockage of the inlet air filter from snow.
Investigator assessment
Analysis narrative
The pilot stated that while in cruise flight at 1,000' agl, the left engine lost power. He stated he noted black smoke coming from the exhaust and he feathered the propeller. The pilot stated the airplane would not maintain altitude and he did not think he could make it back to an airport, so he landed the airplane gear-up on a river bed. Post accident inspection revealed the left engine inlet air filter was blocked by snow. The right engine filter was also found contaminated with snow. Spark plug inspection revealed the engine had been running with a rich mixture.
Source record
Factual narrative
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