General Aviation News will often reprint excerpts from US National Transportation Safety Board (NTSB) accident reports, including this August 2009 report (NTSB Identification: WPR09CA421) that involved an Air Cam in Hamilton, Montana that had performed a soft field landing on an unimproved surface.
According to the accident report, a pilot was performing takeoffs and landings on a river sandbar without incident until the last landing. At this point, a main landing gear wheel separated after an attachment weld sheared and according to witnesses, the wheel rolled towards them and then into the river.
The pilot then performed a go-around but when he landed back at the departure airport, he could not maintain directional control of the aircraft. Hence, the aircraft hit objects and suffered substantial damage to its right fuselage (but there were no injuries).
The probable cause of the accident was ruled the separation of the right main landing gear wheel after contact with soft terrain while a contributory factor was the pilot’s decision to land on an unimproved soft field surface. In other words and if you plan to make any soft field landings or take-offs, make sure that you know how good the surface is that you plan to use.