What happened
The aircraft was fueled the night before the accident, and the tanks were confirmed to be full during a preflight inspection on the morning of the accident. Prior to the accident flight, another company pilot operated the aircraft for 10 sightseeing flights with the mixture set to full rich. During these preceding flights, fuel quantity gauges indicated decreasing levels, dropping from above one-half to below one-fourth during the final sightseeing flight.
The accident pilot took over the aircraft after it had been operated for 3.75 hours since fueling. While the pilot reported performing a visual check of the fuel tanks, the adult passengers on board stated that no such check occurred. Following departure, the engine quit at 200 feet MSL as the pilot reduced power to 25 inches of manifold pressure. The pilot executed a forced landing in a field, touching down with full flaps at an indicated airspeed of 80 knots. Upon touchdown, the nose landing gear separated from the aircraft, and the airplane collided with a sand dune approximately 6 to 8 feet high, coming to rest inverted on top of the dune.
The investigation
Investigators examined the fuel lines at the fuel selector valve, the reservoir fuel tanks, and the fuel control unit, but found no fuel present. No fuel was located in the auxiliary fuel pump, the engine-driven fuel pump, or the reservoir tanks. The fuel selector was positioned to the right fuel tank, which contained a calculated 7 gallons of fuel, with 3.5 gallons being unusable.
Testing of the engine on a test stand showed it operated normally after impact-damaged components were repaired or replaced. While the fuel gauges were found to be operative, testing of the fuel transmitters revealed several discrepancies. Data indicated an average fuel consumption of 15.14 gallons per hour over a nine-day period; at the time of the accident, the aircraft had been operated for 3.79 hours since fueling.
Further investigation into maintenance and procedures revealed that the operator's policy required pilots to dip the tanks during preflight and the chief pilot to perform random checks during the day; however, neither check was performed for this flight. The tool used for dipping the tanks was a wooden paint stirrer with only a "full" mark annotated, lacking any graduated markings. The aircraft had been inspected 48 hours prior to the accident.