What aircraft was involved and where did it happen?

The accident on 2013-05-24 involved a aircraft, registration HI-411, at DO.

What was the probable cause of the accident?

The accident was caused by a catastrophic internal engine failure involving the breakage of the number four piston connecting rod, which resulted in a loss of power and forced an emergency water landing.

Engine failure leads to emergency water landing in Samaná

A Cessna U-206G performing a commercial flight in the Dominican Republic was forced to make an emergency landing on a beach following a catastrophic engine failure.

What happened

On May 24, 2013, at approximately 3:25 p.m., a Cessna U-206G, registration HI 411, was conducting a commercial passenger flight from Punta Cana International Airport to Santiago Cibao International Airport. While cruising at 10,500 feet over the Haitises region, the aircraft experienced a sudden engine failure characterized by a loss of power, a drop in RPM, and intense vibrations through the control column.

The pilot declared an emergency with Santo Domingo Air Traffic Control and attempted to divert to Arroyo Barril Airport in Samaná. However, as the aircraft crossed Samaná Bay and aligned with the runway, it lost significant altitude. Realizing the airport was unreachable, the pilot notified the passengers and executed an emergency water landing (ditching) at Los Róbalos beach, approximately two miles west of the aerodrome. The aircraft struck the water at a depth of about three feet, causing the nose gear to detach. All 5 occupants (the pilot and four passengers) were able to evacuate the aircraft without injury.

The investigation

The CIAA investigation included a visual inspection of the wreckage, interviews with the pilot, and an examination of maintenance records. Investigators examined the engine and flight controls, and performed toxicological testing on the pilot, which returned negative for all substances.

Upon inspecting the Continental IO-520F engine, investigators found that the upper crankcase had been ruptured in two places by the connecting rod of cylinder number four. The connecting rod for piston number four was broken, and the connecting rod bolt (big end) was found outside the engine near cylinders four and six. While the aircraft sustained substantial damage due to the corrosive nature of the seawater, the airframe remained largely intact.

Findings

The primary cause of the accident was a mechanical failure of the engine, specifically the breakage of the connecting rod of piston number four.
The resulting loss of power and severe vibration forced the pilot to deviate from the planned route and ultimately perform the emergency landing.
The nose landing gear was detached from the aircraft due to the impact with the water during the ditching.
The operator did not submit the engine to the manufacturer for a detailed teardown analysis, as they declined to incur the costs following the insurance settlement.