Background
The airplane had been parked for at least 16 days with the inboard fuel tanks approximately one-third full. On the day of the accident, the tanks were filled.
Sequence of Events
After departure, the flight returned to the airport with a report that the flaps were not operational and the landing gear would not retract. A mechanic who had recently worked on the hydraulic system performed an operational check of the flaps more than ten times; no discrepancies were noted. The airplane was not placed on jacks for an operational test of the landing gear.
The flight then departed again. During the initial climb, the pilot advised the air traffic controller that the engine was running rough. The airplane was observed to bank left, pitch nose down, and impact the ground.
Postaccident Examination
Water was detected at the fuel injector nozzles and the fuel manifold assembly of several cylinders of the left engine. No evidence of water contamination was found by operators of other airplanes that had been fueled from the same source.
Postaccident examination also revealed that the left propeller was not feathered, the flaps were partially extended, and the landing gear was fully extended.