What happened
On the day of the accident, the pilot had fueled the aircraft the previous day with enough fuel for a two-hour flight plus a one-hour reserve. During the en route portion of the flight, the pilot initiated a descent from 9,500 feet to 1,800 feet over the northeast side of Lake Washington. At this time, the pilot experienced the first indication of an engine issue. The pilot reported that there were no sudden sounds or engine choking; instead, the engine power smoothly diminished to an idle sound over approximately one second.
After noticing the power loss, the pilot turned to search for a landing site and notified air traffic control of the situation. Unable to locate a suitable landing spot, the pilot attempted to reach an open field near Sand Point along the west shoreline of the lake. During the descent, the pilot switched the fuel selector from both tanks to the left tank and then to the right tank, but the engine failed to restart.
The pilot was unable to reach Sand Point and maneuvered for a ditching parallel to the shoreline. The aircraft collided with the water and remained upright. All 3 occupants were not injured and successfully egressed from the aircraft before it sank. A nearby motorboat operator rescued the crew within minutes.
The investigation
Following the accident, the aircraft was recovered. After the engine was dried out, it underwent an engine run test. The engine started on the first attempt and ran at idle power for several minutes without any noted anomalies.