Accident Overview
The pilot had been conducting superphosphate spreading operations in the area two days prior to the accident, completing approximately 60 trips. On the morning of the accident, he had just completed the sixth load when the outboard section of the right wing struck powerlines. The impact tore the right wing from its attachment points, causing it to separate from the aircraft. Subsequently, the aircraft impacted the ground in a steep nose-down attitude and came to rest 169 meters from the powerlines.
Examination and Findings
A detailed examination of the aircraft and its systems failed to reveal any defect that could have contributed to the accident. The engine was operating at high power at the time of impact. It was noted that the pilot was not wearing a shoulder harness and that an unapproved modification had been made to the lap harness. The toggle fitted to the lap harness was a type approved for 9 to 12g applications only and therefore was not suitable for agricultural operations, which require equipment capable of withstanding 25g loads.
Contributing Factors
Investigators determined that the pilot did not see or avoid the powerline. It is probable that the pilot forgot about the presence of the powerlines.