What happened
The airplane was operating under night visual flight rules when it suffered a total loss of engine power. Unable to maintain altitude or continue the planned flight path, the pilot initiated an emergency procedure for a forced landing. The aircraft was landed in an open field with the landing gear remaining in the retracted position.
The investigation
Following the accident, investigators conducted a post-accident examination of the airframe and propulsion system. A detailed inspection revealed that the engine crankshaft had fractured. To determine the root cause of this structural failure, further laboratory tests were performed on the damaged component.
Findings
Despite extensive laboratory analysis, the specific cause of the fatigue fracture could not be identified. The examination confirmed the mechanical failure but did not reveal why the fatigue crack initiated or propagated to the point of catastrophic separation.