Overview
Pilots were participating in a Grand Prix air race. After a normal preflight inspection, they took off and crossed over the airport for race timing purposes. A climb was initiated on the race course.
Flight and Emergency
Shortly after beginning the climb, the engine began losing power. The aircrew turned the aircraft back toward the airport. The engine then began to run rough and subsequently quit. During a forced landing in a muddy field, the nose gear collapsed and the aircraft stopped abruptly.
Engine Examination
An examination of the engine revealed that a connecting rod had failed and punctured the crankcase. Bearing damage was evident throughout the engine, reflecting a lack of lubrication. Two magneto drive cushions were found blocking the oil system pick-up tube. These were in addition to the two cushions that were properly installed in the magneto drive system. An opening between the accessory section and the oil sump would allow the cushions to enter the oil sump.