The ATSB reports that Soon after the departure, as the aircraft climbed through about 4,500ft, "the pilot noticed engine RPM reducing. The pilot reduced power and attempted to determine a reason for the power loss. The pilot was unable to determine a reason for the power loss and elected to advance the throttle to use remaining power to maintain height. About a minute after advancing the throttle, the engine failed.
The pilot then identified a field as suitable for a forced landing, and conducted a left circuit into the field. During the landing roll, the left main landing gear partially collapsed.
The pilot and passenger were not injured, the aircraft sustained minor damage."
You can read more at the ATSB website: https://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-063/