Accident Overview
An airplane was substantially damaged during a forced landing following a loss of power in both engines while in cruise flight. The pilot reported that one engine began to sputter. He responded by switching fuel tanks and verifying that the mixture was set to full rich. Shortly thereafter, the other engine also began to sputter.
Forced Landing
The pilot then set up for a forced landing into a small field. However, he overshot his intended touchdown point and the airplane impacted trees adjacent to the field.
Preflight Fueling
Prior to departure, the pilot stated that he requested the FBO line service personnel to top off the inboard main fuel tanks. He also reported that he verified the fuel tank caps were present and secure, but he did not remove any of the fuel caps to visually check the fuel quantity.
Fuel Service Discrepancy
The FBO line service personnel who fueled the aircraft stated that the pilot requested the outboard fuel tanks be topped off. During an interview, when questioned about the configuration of the fuel cap, the service personnel reported that the tanks he fueled had standard, twist-off caps.
Aircraft Fuel System Configuration
The aircraft was configured with three fuel tanks in each wing: the production inboard and outboard main tanks, and the auxiliary wing tip tanks. The inboard and outboard main tanks were configured with a sub-flush fuel cap that was covered by a small, hinged panel. The auxiliary tank fuel cap was a standard, twist-off type. This cap protruded above the wing contour and was not covered by a secondary panel.
Post-Accident Examination
During the on-scene investigation, the inboard main fuel tanks were found empty. The outboard main tanks contained fuel, but an exact amount could not be determined. Both wing tip tanks were separated and ruptured.
An examination of each engine was conducted. The fuel flow divider units for both engines were disassembled and did not contain any fluid. The diaphragms were intact. No other anomalies were noted.