What happened
The aircraft had been fueled the day prior to the incident. On the day of the accident, the flight proceeded from its origin to Miami International Airport, where two passengers boarded before the flight continued to Cuba. During a preflight inspection in Cuba, the pilot confirmed that the main and auxiliary fuel tanks contained sufficient fuel. The flight proceeded normally through Cuban airspace, reaching an altitude of 8,000 feet.
Upon reaching the TADPO intersection, the pilot detected a strong odor of fuel within the cabin, though engine instruments remained stable. As the aircraft approached Marathon, approximately 10 to 12 miles out, a burning smell resembling plastic or paper became apparent. The pilot issued multiple pan-pan calls to air traffic control. Shortly after, the right engine began surging and missing, and the pilot observed fire near the louvers on the right engine cowling.
After securing the right engine, the fuel fumes intensified, causing eye irritation. The pilot declared an emergency and began a descent at blue line airspeed. Roughly five minutes after the initial engine issues, the left engine began exhibiting similar surging and missing behavior. The pilot secured the left engine, though the propeller failed to feather completely. At an altitude of 400 feet, the pilot deployed full flaps and the landing gear in preparation for a ditching, a procedure that deviated from the approved flight manual. The pilot intentionally stalled the aircraft just feet above the water surface and evacuated using a life vest. The aircraft sank immediately, and the pilot was rescued 20 minutes later.
Findings
Investigations by the FAA and NTSB found no evidence of an in-flight fire within the engine compartments or the right engine cowling. The left engine showed no signs of malfunction or preimpact failure, and the left magneto functioned correctly during testing. While the right magneto had a broken distributor block and a bent electrode tang, investigators could not determine when this damage occurred.
An examination of the right engine also showed no evidence of preimpact failure, though the right hand stack assembly had fractured due to overload. Both propellers were found in the feathered position. Additionally, an aluminum fuel line in the cockpit, which had been replaced the day before the accident, showed no signs of leakage or failure.