Event Description
After becoming airborne, the pilot leveled the aircraft and immediately experienced severe engine roughness. The engine's rpm fluctuated widely, causing intense vibrations throughout the airframe. Oil spread across the windscreen, obscuring the pilot's view. The pilot declared an emergency and attempted to return to the departure airport, but engine power continued to drop. Unable to maintain altitude, the pilot selected a nearby parking lot for an emergency landing. During the landing, the aircraft cleared a vehicle in its path, touched down on the lot, overran the paved area, and struck two rows of bushes before coming to rest against a sand dune.
Examination Findings
A post-accident examination of the engine revealed holes in the engine case in the area of the No. 1 exhaust tappet and the No. 3 exhaust tappet. Partial disassembly of the engine disclosed that the No. 3 piston had split in half at the oil control ring and piston ring journal. Additionally, the No. 1 exhaust valve tappet was found to be broken.
Maintenance History
According to maintenance records, the engine had accumulated 771 hours of operation beyond the manufacturer's recommended time between overhaul of 2,000 hours.