WPR17LA153

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.

On July 14, 2017, at 1330 Pacific daylight time, an experimental, amateur-built RV-8, N559JC, was substantially damaged when it was involved in an accident near Spokane, Washington. The pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, after takeoff, the engine began to surge and “acted erratically.” He turned back toward the airport to make an emergency landing. The engine then lost total power and black smoke was visible from the engine compartment. The pilot made a forced landing to an open field, resulting in substantial damage to the airplane. Federal Aviation Administration (FAA) inspectors examined the Mazda automotive engine. Fire damage was noted throughout the engine, with some debris found in the throats of both intake openings and on the forward face of the alternator, which was located directly behind the air filter assembly. The debris was consistent with molten foam air filter element. The oil, coolant, and fuel hoses appeared intact. The oil and oil filter element were examined with no metal contamination identified. Internal continuity of the engine was accomplished by manual rotation of the engine via the propeller; movement of the alternator belt at the rear of the engine was observed when the propeller was turned. The FAA inspectors reported that molten debris was beneath and behind the intake air filter assembly, but not forward of it.