Incident Overview
While attempting a normal landing, the private pilot lost directional control of the airplane. The flight instructor, seated alongside, tried to regain positive control but found the flight controls unresponsive. As the airplane drifted to the right, the instructor elected to land on the grass adjacent to the runway.
Landing and Collision
During the landing roll on the grass, the airplane collided with a draining ditch. The impact caused the nose gear to collapse, and the airplane subsequently nosed over. Neither the private pilot nor the flight instructor reported any mechanical issues with the airplane prior to the incident.
Post-Accident Examination
A post-accident examination of the flight control surfaces revealed no mechanical failures. All flight controls were found to be functional and without anomalies. The investigation did not identify any pre-existing mechanical problems that could have contributed to the loss of control.
Conclusion
The incident occurred due to a loss of directional control during the landing phase. The flight instructor's attempt to intervene was unsuccessful because the controls were unresponsive. The decision to land on the grass was made to mitigate the situation, but the presence of a draining ditch led to structural damage and the airplane nosing over.