What happened
The pilot reported that he was operating at an altitude of 6,000 feet under instrument meteorological conditions (IMC). The weather included light to moderate rain and turbulence. During the cruise phase, the pilot heard a loud bang, immediately followed by a loss of power in the left engine.
In response to the mechanical failure, the pilot shut down the affected engine and feathered its propeller. He notified air traffic control (ATC) of the situation. ATC cleared him for a descent to 3,000 feet, which the pilot complied with.
The pilot stated that he was unable to maintain altitude using only the operating engine at full power. Consequently, he attempted a precautionary landing on Interstate Highway 35. He descended at a rate of 200 to 300 feet per minute while maintaining an airspeed of 98 miles per hour (85 knots). Throughout this maneuver, he continued attempts to restart the left engine.
Due to low visibility, ongoing rain, and the presence of vehicular traffic on the highway, the pilot abandoned the approach to the road. He instead executed a wheels-up landing in a pasture.
The investigation
Following the incident, mechanics performed an examination of the engine and conducted a runup test. These inspections did not reveal any discrepancies or mechanical faults that could explain the initial loss of power.