Incident Overview
During cruise flight, the pilot heard several "pops" from the engine, with no changes in oil pressure or temperature noted on the gauges. Shortly thereafter, the engine seized and the propeller stopped turning. Realizing she would not reach her destination airport, the pilot began searching for a suitable landing area. Her options were limited by cars and power lines.
Forced Landing
The pilot eventually located a road that was flat and free of cars and power lines, though natural desert vegetation was present. After touchdown, the left wing struck a tree, causing the airplane to ground loop.
Aircraft and Engine Details
The pilot stated that the airplane was a homebuilt replica equipped with a 1929 Wright Whirlwind R540A engine. Post-incident inspection of the engine revealed a large hole on the right side of the engine case. Investigators noted that damage to other cylinders and connecting rods appeared to have been caused when the number 3 articulating rod separated and began moving inside the engine. The engine seized when the number 3 articulating rod bent the number 4 articulating rod and then moved into the bottom of the number 5 cylinder, forcing itself between the bottom of the piston and the master rod.
Investigation Findings
The underlying cause of the number 3 articulating rod's separation could not be determined.