yep, wet grass. like being on ice.
https://data.ntsb.gov/carol-repgen/api/ ... 194636/pdf
Analysis
The pilot reported that, while landing on a wet grass runway, the airplane began to slide, and he was unable to stop before the airplane departed the end of the runway into a soft, wet soybean field. The main landing gear dug into the soft soil and the airplane nosed over which resulted in substantial damage to the vertical stabilizer, empennage, and right wing. The pilot reported that there were no pre-accident mechanical malfunctions or failures with the airplane that would have precluded normal operation.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s inability to stop the landing roll on a wet grass runway which resulted in a runway overrun.