What happened
While cruising at 6,000 feet MSL, a propeller blade from the left propeller assembly separated from the aircraft. The departing blade penetrated the fuselage, which severed electrical lines and resulted in a total loss of electrical power.
At the time of the incident, the aircraft was flying in IMC. To seek better weather conditions, the pilot performed a 1el-degree turn. For approximately 40 minutes, the pilot operated the aircraft without electrical power or most flight instruments. After reaching an area of clear weather and successfully identifying his location, the pilot executed a gear up landing at the nearest airport. The pilot was not injured.
The investigation
A metallurgical examination of the separated blade was conducted to determine the cause of the failure. The analysis revealed that the separation was caused by fatigue cracking. These cracks originated from multiple sites located within corrosion pits found in the balancing hole.