On April 15, 2016, about 1010 eastern daylight time, a Cessna U206F, N1346Q, was ditched in the international waters of the Atlantic Ocean about 23 nautical miles east of the shoreline of North Miami Beach, Florida. The private pilot and two passengers were not injured. The airplane was not recovered; therefore, it was considered to be substantially damaged. The airplane was registered to Aircraft Guaranty Corp Trustee, and operated by a private individual under the provisions of 14 Code of Federal Regulations as a Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The flight originated from Fort Lauderdale Executive Airport (FXE), Fort Lauderdale, Florida, about 0955, and was destined for South Bimini Airport (MYBS), North Bimini, Bahamas. The pilot stated that prior to departure of the accident flight he performed a preflight inspection, which included a check of the oil quantity and noted that it was full. The preflight inspection and engine run-up before takeoff were satisfactory with no discrepancies noted; the oil pressure was satisfactory. The flight proceeded with visual flight rules flight following, and when they were about 20 minutes from the destination, the pilot noted a rapid decrease in oil pressure, and saw smoke coming from the engine cowling. The engine then ceased producing power, and he declared an emergency with the air traffic controller. He briefed the passengers about the ditching procedures, and ditched the airplane near two boats. All occupants exited the airplane, boarded a life raft, and shortly thereafter he noticed another airplane orbiting their position. They were rescued by a yacht that motored to their location. The airplane permanent maintenance records were on-board at the time of the ditching and were not recovered. The day before the accident, the engine oil and oil filter were changed by an airframe and powerplant mechanic with inspection authorization (this same mechanic had maintained the airplane for several years). As part of his procedure, he visually inspected the oil filter adapter and did not see any evidence of oil seepage or leakage. He also checked the oil filter adapter and confirmed it was tightly installed. He reported torqueing the Tempest AA48108-2 oil filter to the recommended value of 16 ft/lbs and safety wired it. Following the oil and oil filter change, he ran the engine twice, to about 1,800 rpm, with the engine cowling installed and noted no issues. After each engine run he checked the engine compartment for oil leaks and did not find any associated with the oil change. While in the engine compartment he did notice dampness at the starter adapter pulley. As part of his oil change he also cut open the oil filer and inspected the filter element finding only carbon deposits (normal), but no metal. He did not submit a sample of oil for oil analysis testing. He returned the airplane to service by making a hand written entry in the permanent maintenance records; he did not make a copy of the entry. After hearing of the ditching, he inspected the ramp where the airplane had been parked after the oil change and he did not find any evidence of oil leakage on the ground. Documents provided by the airplane owner indicated the engine was overhauled by a Federal Aviation Administration (FAA)-approved repair station in August 2007, and subsequently installed in the airplane. According to FAA airworthiness records, in May 2008, an oil filter adapter was installed in accordance with Supplemental Type Certificate (STC) SE09356SC. The STC replaced the original engine metallic oil screen and allowed for the installation of a full flow oil filter. The mechanic who installed the oil filter adapter, and who was the same mechanic who performed the most recent oil change, reported applying anti-slippage material in two places at installation. The first place was at the top of the hex head that was torqued and safety wired, and the second place was at the bottom of the casting of the adapter where it met the accessory case of the engine. According to the pilot, the engine had accrued approximately 700 hours since major overhaul at the time of the accident. A review of the oil filter adapter Instructions for Continued Airworthiness specify to inspect for oil seepage, to inspect the safety wire for security and integrity, and to inspect integrity of fit. According to the captain of the yacht that rescued the occupants, the water depth in that area was about 2,360 feet. Because of the depth, the insurance adjuster indicated the airplane would not be recovered, and could not be examined. The airplane was ditched in international waters of the Atlantic Ocean; therefore, in accordance with ICAO Annex 13 as State of Registry, the investigation was the responsibility of the U.S. Government National Transportation Safety Board.