Background
A pilot was flying a potential buyer on a pre-buy inspection flight. The aircraft had just been leveled in cruise flight when the engine momentarily lost power. The pilot applied carburetor heat, and the engine regained normal power.
Accident Sequence
While returning to the airport, the pilot turned the carburetor heat off, then on again. The engine lost power a second time. According to the pilot, engine power could not be restored on this occasion.
Ditching
With no suitable landing sites within gliding distance, the pilot ditched the airplane into water paralleling the shoreline. During the ditching, the airplane nosed over. The left wing sustained substantial damage.
Weather Conditions
Based on the temperature and dew point at the time of the accident, conditions were favorable for serious carburetor icing at any power setting.