What happened
The accident occurred while a commercial pilot was conducting an off-airport landing under Title 14, CFR Part 91 regulations in a tailwheel-equipped airplane. The pilot reported that during the landing roll, the aircraft transitioned from an area of powdery sand to a surface covered with rocks. This change in terrain caused the nose of the airplane to pitch down abruptly.
The pilot stated that he had insufficient aft stick pressure to arrest the nose-down pitch. As a result, the airplane nosed over, resulting in damage to the fuselage, wings, and lift struts. The pilot reported no known mechanical problems with the airplane prior to the accident.
Findings
Contributing factors included the transition from sand to rocks during the landing roll and the pilot's inability to apply sufficient aft stick to stop the nose-down pitch.