What happened
The crew originally planned to perform landing practice at an airport located approximately 20 minutes away, followed by a refueling stop before returning to their departure point. Before takeoff, the crew estimated a fuel endurance of two hours based on fuel gauges and the captain's knowledge of consumption rates; however, the fuel tanks were not physically dipped to verify quantities.
During the flight, which was conducted at 1,500 feet MSL, the crew completed one full-stop landing at the practice airport. During the subsequent takeoff, an engine experienced a momentary overspeed, prompting the crew to decide to return to the original departure airport without refueling. While approaching the departure airport, the aircraft was delayed for approximately seven minutes to perform a manual gear extension.
As the aircraft was roughly 6 miles from the runway, fuel pressure dropped in one engine. Although the boost pumps were activated, that engine lost power. Shortly thereafter, a low fuel pressure light illuminated for a second engine. The captain requested that the flight engineer switch the fuel feed to another tank, but the flight engineer stated that the aircraft was out of fuel. The remaining engines subsequently lost power, and the captain ditched the aircraft into a bay. The total time from the initial takeoff to the ditching was 1 hour and 19 minutes.
The investigation
The investigation noted that the aircraft had flown only 39 hours since its restoration. At the time of the accident, exact fuel capacities, fuel flow calculations, and unusable fuel amounts had not been established. While a dipping chart had been prepared using a yardstick to measure 25-gallon increments, this data had not been verified, and the process of dipping was not included in the standard pre-flight inspection.