What happened
The flight was intended to involve practice landings at a nearby airfield, followed by a refueling stop before returning to the departure point. Before takeoff, the crew estimated a fuel endurance of two hours based on gauge readings and the captain's experience with the aircraft's consumption, though the tanks were not physically measured via dipping. The flight was conducted at an altitude of 1,500 feet msl.
After completing one landing at the practice airfield, the crew attempted a second takeoff. During this phase, an engine experienced a brief overspeed, prompting the crew to abort the practice session and return to the departure airport without refueling. During the approach to the original airport, the crew experienced a seven-minute delay while manually extending the landing gear.
Approximately six miles from the runway, the engine fuel pressure began to drop. Despite activating the boost pumps, the engine lost power, and a low fuel pressure warning subsequently appeared for a second engine. When the captain requested a switch to an alternative fuel tank, the flight engineer indicated that the fuel supply was depleted. All remaining engines subsequently lost power, leading the captain to ditch the aircraft into a bay. The total time elapsed from the initial takeoff to the ditching was 1 hour and 19 minutes.
Findings
Investigations revealed that the aircraft had been in service for only 39 hours since its restoration, and specific parameters regarding fuel capacity, flow rates, and unusable fuel volumes had not been officially established. While a method for measuring fuel levels using a yardstick and 25-gallon increments had been drafted, the data remained unverified. Furthermore, the process of dipping the tanks was not included in the standard pre-flight inspection procedures, contributing to the fuel exhaustion.