What happened
The pilot reported that the engine began to run rough while the aircraft was on the downwind leg of the traffic pattern. In response to this mechanical irregularity, the pilot executed a precautionary landing directed toward the runway.
During the landing phase, the aircraft touched down approximately midway down the available runway surface. However, the aircraft failed to stop within the paved area and ran off the end of the runway. The pilot attributed the overrun to excessive airspeed at touchdown.
The investigation
A postcrash examination of the aircraft was conducted to determine the root cause of the engine's rough running condition. Investigators inspected the engine and associated systems for any mechanical failures or anomalies that could explain the performance issue reported by the pilot prior to landing.
Findings
Despite the pilot's report of an engine malfunction, the postcrash examination revealed no anomalies in the engine or its components that would account for the rough running condition. The investigation concluded that the primary factor leading to the accident was the excessive airspeed at touchdown, which resulted in the aircraft overrunning the runway end.