What happened
While ascending to cruise altitude, the pilot experienced a loss of power in one of the engines. Following this failure, the flight crew was provided with vectors to return to the airport from which they had originally departed. The pilot was cleared to perform a VOR-A approach and confirmed intercepting the inbound radial. However, the aircraft struck the ground to the right of the inbound radial and short of the runway centerline extension. A fire following the impact caused significant damage to the airframe.
Findings
Investigation of the wreckage revealed that the propeller on the left engine was in the feathered position. A metallurgical and visual inspection determined that the turbocharger shaft had failed due to fatigue. It was noted that the shaft contained chromium, despite the aircraft overhaul manual stating that chrome plating or the restoration of such a shaft is prohibited. Additionally, metallographic analysis of the center housing identified a microstructure of grey iron, which is typically used in automotive applications. The turbocharger in question had been overhauled and placed into service on the left engine in October 1989. The accident resulted in three fatalities.