19990920042639A

(.4)The aircraft was parked outside on the ramp for several months, with the fuel drains removed and the tanks drained. An A&P mechanic replaced the fuel drain in the right tank and added fuel for a maintenance ferry flight. The pilot performed a preflight and before takeoff checks. The engine stalled once during taxi, then began to miss and run roughly after takeoff. After returning, the pilot drained the fuel sumps and found a 'small amount of water' in the gascolator. He then drained an additional gallon of fuel from the tank without finding any additional water or sediment. After takeoff on the second flight, the engine began surging and then quit. When attempts to restart the engine failed, he turned back toward the airport but could not reach the runway and ditched the airplane in the water. The mechanic did not perform or offer to perform any additional troubleshooting procedures between the first and second flight. The inside of the gascolator was coated with an insoluble greenish-brown film. The left wing fuel quantity transmitter was coated with material that was similar in appearance to a non-silicon sealant. The material was decomposing and readily flaked off when touched. About 10CC of liquid was recovered from the fuel reservoir; about half was water, with a heavier sediment that was similar in color and consistency as to the material coating the fuel quantity transmitter. The above noted discrepancies were located in areas that would not be accessible or serviceable by a pilot performing a preflight inspection.