Accident Sequence
The airplane was climbing after takeoff when the pilot heard and felt a change in engine operation. The oil pressure and temperature gauges indicated normal readings, but engine rpm briefly spiked beyond redline before returning to a lower value. The pilot turned toward the nearest airport. He reported that "something gave in the engine, and it began to vibrate the yoke." Shortly thereafter, oil splattered on the windshield. The propeller continued to turn, but the airplane could not maintain altitude. The pilot executed a glide descent, and the airplane struck trees and came to rest in a swamp.
Engine Examination
Examination of the engine revealed cracks and a hole in the top of the crankcase. The No. 5 connecting rod cap was separated, with pieces of the rod cap and bolts found in the engine sump. The fracture features of the rod cap and bolts were obscured by mechanical damage. No evidence of oil leakage from engine seals or at the propeller hub was observed.
Maintenance History
The connecting rods had been replaced during an engine major overhaul completed on July 13, 1992. On April 14, 2005, a new McCauley propeller was installed in accordance with Supplemental Type Certificate SA433CH, and an annual inspection was performed on the same date. At that time, the engine had accumulated 1141.2 hours since major overhaul. The engine had operated for 9 hours since the annual inspection, and the pilot reported no engine anomalies during those flights.