What happened
The aircraft was conducting its initial flight following a recent engine overhaul. Shortly after departing, oil from the engine began spraying onto the pilot's windshield, obscuring vision. In response to the situation, the pilot shut down the engine and attempted to return to the airport. However, the aircraft was unable to reach the runway and instead landed in a rough field.
The investigation
A teardown of the engine was performed to determine the source of the oil spray. The inspection revealed that an incorrect crankshaft oil seal had been installed during the overhaul process, which subsequently became dislodged during flight. Furthermore, investigators discovered damage to both the crankshaft and the crankcase. This specific damage was attributed to the misalignment of the crankcase halves, which had occurred during a previous modification.