What happened
During a nighttime flight at an altitude of approximately 4,000 meters, the crew provided a routine position report to Air Traffic Control, indicating that the flight was proceeding normally. Roughly ten minutes following this communication, the aircraft disappeared from radar surveillance.
The plane subsequently crashed into the Atlantic Ocean, located approximately 180 km northwest of the Irish coastline. Search and rescue operations were initiated immediately, leading to the discovery of various debris and remains during the early morning hours. Following several days of searching, all recovery efforts were halted, and it was determined that all 99 occupants had perished.
Findings
Official investigators were unable to determine the exact cause of the accident with absolute certainty, and they found no conclusive evidence to support theories regarding an onboard explosion. However, the investigation identified a highly probable scenario involving the overspeeding of an outboard propeller.
This malfunction is believed to have been triggered by oil pollution following damage to a gear during the acceleration of an engine supercharger. The presence of metal particles within the regulator valves likely prevented the propeller from feathering and caused the pitch to decrease. Such a rapid mechanical failure could create significant flight disturbances that are difficult for a crew to counteract in time, especially since identifying the specific nature of the malfunction requires critical time.