What happened
A commercial pilot was operating a tailwheel airplane equipped with tundra tires on a public use flight under 14 CFR Part 91. The mission was being conducted in support of federal law enforcement activities, involving an approach to an off-airport landing site.
During the landing roll on an unimproved strip of tundra, the right main wheel struck an unseen ledge followed by a hole. This impact caused the aircraft to nose down. The pilot reported that there were no known mechanical anomalies with the aircraft prior to the accident.
The investigation
The aircraft sustained a broken engine mount as well as structural damage to the forward fuselage and the firewall.