What happened
On December 30, the aircraft experienced a failure of engine number four. The plane was grounded in Lisbon for maintenance, during which the faulty engine was replaced. Before resuming operations to London, the crew conducted a local test flight. Approximately twenty minutes after takeoff, issues arose with engine number three, which subsequently caught fire. The crew initiated a return to the airport. While descending to an altitude of 1,200 feet, the aircraft suffered severe vibrations, and smoke filled both the cabin and the cockpit. The pilot was unable to feather the propeller on the affected engine. Consequently, the seaplane named Golden Horn lost control and crashed into the bay approximately 800 meters offshore. Two individuals, a radio operator and a passenger, were rescued from the water, while 13 other occupants perished in the incident.
Findings
The official investigation determined that a technical failure on the fourth piston of the sixth cylinder in engine number three was the primary trigger. This malfunction caused hydraulic fluid and gasoline to leak and ignite upon contact with high-temperature components. The loss of control occurred because the pilots were incapacitated by the fire spreading through the cockpit. Additionally, the high casualty count was attributed to the crew's failure to follow emergency procedures and the fact that passengers were not properly secured or prepared for an emergency landing. It was also noted that all passengers on board were unauthorized.