Incident Overview
During takeoff on a gravel and dirt runway, the aircraft collided with a fence, causing the tailwheel to be pulled out of the empennage. The pilot stated that the dump valve failed to operate or became stuck, preventing the jettisoning of the chemical load. He had felt the need to dump the load after hitting a 'softspot' in the runway surface, which was soft and muddy in places.
Aircraft Loading and Damage
The aircraft was loaded with 20 gallons of fuel and 170 gallons of chemicals at the time of the incident. Following the collision with the fence, the tailwheel was detached from the empennage. Despite this damage, the pilot was able to maneuver the aircraft back to the runway and execute a landing without any further issues.
Pilot Report
The pilot reported that the runway condition—soft and muddy in spots—contributed to the need to consider dumping the load. However, due to the dump valve malfunction, he could not jettison the chemicals. The impact with the fence occurred during the takeoff roll or initial climb.