Pre-Purchase Inspection and Purchase
A mechanic performed a pre-purchase inspection of the aircraft. The inspection detected no malfunctions with the fuel system. The mechanic informed the pilot that the aircraft was overall 'in good condition.' Later that day, the pilot purchased the aircraft.
Flight and Fuel Indications
After purchase, the pilot observed that the main fuel tanks were virtually full and then took off. According to the pilot, with full main fuel tanks the aircraft's endurance would be 2.8 hours. During the flight, the pilot observed the fuel gauges for the main tanks; they indicated fuel levels at one-half and one-quarter capacity.
Power Loss and Forced Landing
Ten minutes after the fuel gauge observations, both engines lost all power. The pilot performed a forced landing in an underlying soft field.
Examination Findings
Examination of the fuel tank bladders revealed that some of the snap fasteners designed to secure the tops of the bladders were excessively weather checked and had shrunk.