Accident Overview
During a local sightseeing flight, the pilot noticed a partial loss of engine power. He initiated a turn back toward the airport while troubleshooting the issue. Despite his attempts, the engine would not regain full power and continued to surge and sputter randomly. The pilot entered the airport's traffic pattern on the downwind leg. On final approach to the runway, the airplane encountered multiple downdrafts and wind gusts. It is likely that, due to the downdrafts and the partial loss of engine power, the pilot was not able to maintain airplane control. The airplane subsequently landed hard short of the runway surface and nosed over, coming to rest inverted.
Environmental Conditions
The reported wind conditions around the time of the accident varied between 20 and 70 degrees right of the runway heading and were 14 knots gusting to greater than 20 knots. A company pilot who landed about 8 minutes before the accident reported that he encountered strong downdrafts and windshear while on final approach to the runway and that he would not have been able to reach the runway if he had a partial or total loss of engine power.
Postaccident Examination
Postaccident examination of the airframe and engine revealed no evidence of any preexisting mechanical malfunctions or failures that would have precluded normal operation. The engine was subsequently installed on a test stand and was successfully run through various power settings for several minutes. The reason for the partial loss of engine power could not be determined.
Probable Cause
The probable cause of the accident is the pilot's inability to maintain aircraft control due to a partial loss of engine power and an encounter with downdrafts and gusting crosswinds while on final approach to the runway. The reason for the partial loss of engine power could not be determined because postaccident examination revealed no mechanical malfunction or failure that would have precluded normal operation.