Summary
The pilot, who also served as an A&P mechanic, conducted a post-maintenance flight after calibrating the fuel flow on the right engine's fuel injector pump. During cruise, flames were observed. The engine was shut down and feathered. After landing, the aircraft could not be taxied and was abandoned.
Narrative
Prior to the maintenance inspection flight, the pilot/owner—a certificated airframe and powerplant mechanic—had been calibrating the fuel flow on the right engine fuel injector pump. As part of this procedure, an external line had been connected to the fuel flow transmitter fitting of the fuel injector. Before the test flight, the external line was removed and the fuel flow component was replaced. About ten minutes after takeoff, the pilot observed flames coinciding with a drop in oil pressure from 25 to 15 psi. The right engine was shut down and its propeller was feathered. After landing, the pilot was unable to taxi the aircraft, and the aircraft was subsequently abandoned.
Probable Cause
The official probable cause findings state that the fire occurred during cruise phase. The findings include: improper fuel system line fitting, improper maintenance installation by the pilot in command, a leak in the fuel system line fitting, and fuel system fire.