Amateur-built VANS RV8 N559JC accident near Spokane, Washington

Probable cause

An inflight engine fire for reasons that could not be determined based on the available information, which melted the air filter element and obstructed the engine's air intakes, resulting in a total loss of engine power.

NTSB analysis

The pilot reported that, shortly after takeoff, the engine began to "act erratically" and surged. The pilot initiated a turn back toward the airport, during which the engine lost total power and began producing black smoke. The pilot subsequently performed a forced landing to an open field, during which the airplane sustained substantial damage.

Examination revealed that the automotive engine's air filter element had sustained fire damage, and debris consistent with molten air filter material was in the throats of both intake openings. It is likely that the engine lost power due to ingestion of molten foam air filter, which obstructed the air intakes; however, how the filter became fire-damaged was not determined. There were no other mechanical anomalies that would have precluded normal operation of the engine.

Text from the NTSB. Open the NTSB docket for WPR17LA153 for the full record.