What happened
Shortly after departing on its flight, the crew of the aircraft experienced a critical mechanical failure involving the number four engine. During the emergency procedures following this initial failure, the crew attempted to reduce the aircraft's weight by dumping fuel. During this process, the number two engine began to overheat. Faced with multiple engine issues, the crew made the decision to perform an intentional ditching of the aircraft.
Following the incident, the wreckage remained submerged for approximately two weeks before it could be retrieved. Upon recovery, the aircraft was found to be significantly damaged, with roughly 50% of the structure lost to corrosion.
Findings
Investigation into the cause of the initial engine failure was hindered by the environmental conditions. Because of the extensive damage caused by salt water corrosion, investigators were unable to identify any malfunctions or failures occurring in the number four engine prior to the impact.
Additionally, the investigation noted several regulatory and maintenance documentation gaps. There was no evidence that the operator or the aircraft held the necessary CFR Part 129 certificate authority. Furthermore, investigators could not verify the service history for the aircraft, engines, propellers, or time-change components, nor could they confirm compliance with relevant airworthiness directives.