What happened
Prior to takeoff, the pilot conducted an engine run-up. During this procedure, the pilot observed that the carburetor heat handle felt "loose" after the heat was removed. As the aircraft entered its initial climb, the engine suffered a partial loss of power, and black smoke was seen exiting the exhaust. While the pilot was maneuvering to return to the airport, the airplane stalled and crashed into water.
The investigation
An examination of the engine found no mechanical failure or malfunction. However, investigators discovered that the carburetor heat control cable had separated from the carburetor heat control arm assembly.
Upon disassembling the carburetor, evidence was found of previous fuel leakage from the carburetor bowl vent, a condition that would introduce excess fuel into the air induction system. Additionally, the head of the float needle valve and the adjustment tab of the metal float were found to be worn. The carburetor had been installed on the engine on June 3, 1996, and had accumulated 1,246 hours of use at the time of the accident. According to the pilot, the worn condition of the carburetor had been known for the past seven years.