Incident Overview
A pilot reported that after refueling and loading chemicals at a field location, the helicopter took off. Approximately one minute into the flight, a loud bang was heard, followed by vibrations. The pilot initiated a forced landing toward a dirt road. However, before touchdown, the helicopter began to spin and subsequently struck trees in a slightly nose-low attitude.
Post-Accident Examination
An inspection of the helicopter revealed that one tail rotor blade had separated about 10 inches from the hub. Further examination showed that the ballast weight on the aft portion of the tailboom was partially disconnected, secured only by its forward retaining pin.
Previous Maintenance Issue
According to ground crew, the day before the accident, they observed the ballast weight disconnected at its aft attaching point and informed the pilot. The pilot then reinstalled the ballast weight and secured it with the retaining pin. One ground crew member noted that "the pin seemed to lock in place."
Sequence of Events
The pilot reported the sequence as a loud bang, vibration, forced landing attempt, spin, and tree impact. The examination findings point to the tail rotor blade separation and ballast weight condition, but the source does not explicitly state a causal relationship between these factors and the accident.