Background
N3025W departed on a ferry flight with a temporarily installed fuselage fuel tank that was not secured. The computed center of gravity (C.G.) at takeoff showed the aircraft approximately 0.9 inches aft of the aft limit. The ferry tank installation had not been approved. The pilot, new to this type of work, reportedly did not know how to operate the ferry tank system. The takeoff position of the ferry tank was estimated; after being filled, it had pushed out the fuselage baggage door and had to be pushed back in.
Sequence of Events
The aircraft climbed to 7,000 feet when the controller observed the aircraft making erratic turns. The pilot transmitted, "We have problems." There were no further communications with N3025W. The aircraft subsequently broke up in flight. The forecast the pilot received included moderate turbulence and rain showers.
Contributing Factors
It was considered likely that the unsecured tank would have migrated during flight, changing the center of gravity, altering longitudinal control forces, and causing pitch control problems in turbulence.