What happened
The aircraft 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 refilled. Shortly after departure, the flight returned to the airport, reporting that the flaps were non-operational and the landing gear would not retract.
During the initial climb following the subsequent departure, the pilot notified the air traffic controller of a rough running engine. The aircraft was then observed to bank to the left and pitch its nose downward before impacting the ground. There were no injuries reported.
The investigation
Investigators found water at the fuel injector nozzles and the fuel manifold assembly of several cylinders within the left engine. However, inspections of other aircraft fueled from the same source showed no evidence of water contamination.
A mechanic who had recently performed work on the hydraulic system had operationally checked the flaps more than 10 times without noting any discrepancies. Notably, the aircraft was not placed on jacks for an operational test of the landing gear following this maintenance. Post-accident examination of the wreckage revealed that the landing gear was fully extended, the flaps were partially extended, and the left propeller had not been feathered.