What happened
During the takeoff roll at a remote grass airstrip, the aircraft struck a mound of dirt created by a burrowing animal. This impact caused the aircraft to suddenly veer to the right. The pilot attempted to correct the deviation by applying left rudder, but was unable to maintain the proper takeoff heading before the aircraft departed the right side of the runway surface.
After leaving the paved or prepared surface, the landing gear rolled over several large rocks located nearby. This resulted in the right wing impacting a tree situated near the edge of the airstrip. The pilot was not injured during the event.
Findings
The dirt mound that caused the excursion was not visible to the pilot during the takeoff roll because it was obscured by tall grass and weeds. Additionally, the pilot had not performed a pre-takeoff inspection of the 1,100-foot runway to check for obstructions. According to the Idaho Airports Guide, this specific runway surface is known to be rough and prone to ongoing deterioration, with usage recommended only for highly experienced mountain pilots.