Introduction
An accident occurred involving an aircraft equipped with a Lycoming O-360-A1A engine. The engine had been overhauled by a facility in Canada and converted with high-compression pistons and cylinders. After approximately 35 hours of total operation, the engine experienced a partial power loss during an unknown phase of flight.
Engine Examination
Metallurgical examination of the engine revealed that the #2 connecting rod had fractured in two places due to fatigue at the rod end. This fracture resulted in the release of the connecting rod from the crankshaft. No evidence of engine disassembly or maintenance by the owner/builder was found. Post-crash examination of the engine showed holes in the upper engine case and disintegration of the #1 piston.
Sequence of Events
A witness reported observing the aircraft at low altitude over gently rolling terrain trailing black smoke. During this time, the pilot was observed to exit the aircraft. Subsequently, the aircraft rolled into a descending right turn and impacted the terrain approximately 600 feet from the pilot's ground impact. A post-crash explosion and fire ensued.
Post-Crash Findings
Reconstruction of portions of the aircraft revealed sooting and evidence of a pre-impact fire forward of the firewall in the vicinity of the gascolator. Additionally, pre-impact heat damage was found on the Plexiglas windscreen and canopy. The only evidence of heat or fire distress observed during post-mortem examination of the pilot was on the eyebrows and forward hairline.
Canopy Considerations
The aircraft's canopy is airfoil shaped and during flight conditions would tend to create an aerodynamic low-pressure condition near the top of the canopy. If the canopy were opened in flight with fire conditions existing along its forward exterior surface, the entrainment of hot air and fire within the upper cockpit interior environment may have become intolerable for the pilot.