What happened
During the cruise phase of flight, the aircraft experienced a critical malfunction when the fourth engine underwent an overspeed event. In response to this mechanical failure, the crew deactivated the engine and feathered the propeller to stabilize the aircraft.
Shortly after addressing the first issue, the second engine began experiencing intense vibrations. To prevent further damage or loss of control, the flight crew proceeded to shut down this engine and feather its propeller as well. Following the loss of two engines, the aircraft was unable to maintain its altitude and began a steady descent at a rate of 500 feet per minute.
Recognizing the loss of sufficient power to continue the flight, the pilot initiated an emergency descent toward Ilha Grande. The aircraft ultimately performed a belly landing on a beach, where it came to a complete stop. Despite the severity of the engine failures and the nature of the landing, there were no injuries among the 22 occupants on board.
Findings
The incident was characterized by the sequential failure of two engines. The primary factor contributing to the emergency descent was the simultaneous loss of power from both engine number four and engine number two.