Incident Overview
A pilot reported that after reaching a cruising altitude of 9,000 feet, the engine began to 'miss' and indications of oil pressure, oil temperature, and manifold pressure dropped. The pilot attempted to reach the nearest airport while maintaining a descent rate of 500 to 800 feet per minute. Unable to make it to the airport, the pilot selected a field for landing. He reported clearing the surrounding trees and applying flaps to reduce speed. Because the field was muddy, the pilot used the emergency gear extension to lower the landing gear, aiming to prevent the airplane from sliding into the trees. The airplane touched down and slid approximately 25 feet before coming to rest. Substantial damage was sustained to the left wing and fuselage.
Engine and Turbocharger Examination
An engine teardown revealed holes in the crankcase near the number four cylinder. The engine had sustained both thermal and mechanical damage as a result of oil starvation. Additionally, a hole was noted in the turbine wheel shroud on the hot section of the right turbocharger. The turbocharger lacked a data plate, serial number, or model number, but carried part number 466304-0003. The oil inlet and outlet fittings were intact and showed no signs of oil leakage. The turbocharger was disassembled and inspected. The inspection revealed that the turbine wheel shroud had fragmented due to a fatigue failure. Contact signatures from the shroud were found on the back surface of the shaft and wheel assembly.
Maintenance Records
A review of maintenance records showed that both the left and right turbochargers were installed on June 21, 1988. The data plate on the left turbocharger matched the information in the records. Without a serial number on the right turbocharger, it could not be verified that this was the same unit installed on June 21, 1998. However, the maintenance logs provided did not contain a record of the turbocharger having been replaced after that date.