What happened
During the initial phase of takeoff, as the aircraft began its rotation, one of the propeller blades detached from the assembly. The force of the separation propelled the blade approximately 1,000 feet behind the aircraft. With only one blade remaining, the propeller hub and the surviving blade became severely unbalanced. This imbalance exerted significant torque on the engine, twisting it at a 45-degree angle relative to its normal mounting position.
The pilot recognized the catastrophic failure and immediately shut down the affected engine. However, the loss of thrust and the severe mechanical distortion prevented continued flight. The aircraft departed the left side of the runway and cartwheeled across the ground, sustaining substantial damage from the impact and rolling motion.
The investigation
Post-accident examination of the propeller assembly revealed that the failed blade had fractured approximately two inches outboard of the hub. Metallurgical testing provided critical insights into the failure mechanism. Tests identified numerous fatigue origins on both the butt ends of the blade at its separation points, as well as within the propeller attachment area on the face of the hub.
Further inspection showed that the propeller blade mounting component, which connects to the engine, had broken out between two stud holes. This specific area exhibited clear signs of fatigue cracking alongside deformation of the mounting surface, indicating a progressive structural failure prior to the final separation event.