What happened
During the departure climb phase of flight, the pilot experienced a loss of power in the right engine. Following this failure, the pilot attempted a single-engine missed approach back to the departure airport. The pilot reported being high on the approach and subsequently feathered the propeller when executing the missed approach. At the time of the accident, instrument meteorological conditions (IMC) were prevailing.
The investigation
An examination of the right engine identified that the oil return line, which runs from the turbocharger to the scavende oil pump, had become disconnected. There was no evidence of stripped threads on the connectors. Upon removal of the engine's oil pan, investigators discovered metallic debris inside. Maintenance records indicated that the last recorded maintenance for this engine was its installation 31.7 hours before the accident.
Findings
Performance data analysis for the aircraft showed that under field conditions and in a single-engine climb configuration, the aircraft had a positive climb rate of approximately 340 fpm. However, the data also demonstrated that if the propeller is not feathered, there is a loss of single-engine climb performance of 400 fpm. Additionally, using a flap setting of 15 degrees results in a further loss of 200 fpm.