SEA02FA060

The crew had originally planned to practice landings at an airport about 20 minutes away, then stop, refuel the airplane, and subsequently return to the original departure airport. Prior to the flight, the crew discussed fuel endurance, which was calculated to be 2 hours based on the captain's knowledge of the airplane's fuel consumption, and the quantity of fuel indicated on the gauges. The fuel tanks were not dipped. The flight was made at 1,500 feet msl. Upon reaching the practice airport, the crew conducted one full stop landing, then taxied back for takeoff. During takeoff, an engine had a momentary overspeed, and the crew decided to return to the original departure airport without refueling. Approaching the original departure airport, the airplane had to delay landing for about 7 minutes for a manual gear extension. Upon completion, it turned back toward the airport, and was about 6 miles from the runway when fuel pressure for one of the engines dropped. The boost pumps were turned on; however, the engine lost power. A low fuel pressure light then illuminated for another engine. The captain called for the flight engineer to switch fuel feed to another tank, but the flight engineer responded, "we're out of fuel." The remaining engines subsequently lost power, and the captain ditched the airplane into a bay. The time from first takeoff until ditching was 1 hour, 19 minutes. The airplane had flown 39 hours since restoration, and exact fuel capacities, fuel flow calculations and unusable fuel amounts had not been established. A dipping chart had been prepared, with one person in the cockpit and one person with a yardstick putting fuel in a main tank in 25-gallon increments. However, the data had not been verified, and dipping was not considered to be part of the pre-flight inspection.

History of flight

On March 28, 2002, about 1310 Pacific standard time, a Boeing S-307 Stratoliner, N19903, registered to the National Air & Space Museum and operated by The Boeing Company as a 14 CFR Part 91 maintenance check and proficiency flight, ditched in the waters of Elliott Bay, Seattle, Washington, following a loss of engine power on all four engines. Visual meteorological conditions prevailed at the time, and a company visual flight rules flight plan was in effect. The airplane was substantially damaged. The two airline transport pilots, and two airframe & powerplant mechanics seated at the flight engineer and avionics stations were not injured. The flight departed Snohomish County Airport (Paine Field) (PAE), Everett, Washington, and was destined for Boeing Field/King County International Airport (BFI), Seattle, Washington.

The accident flight was the second of two flights that day. The first flight was flown from Boeing Field to Paine Field, where a full stop landing was made. The crew then taxied the airplane back to the approach end of the runway, and took off on the accident flight.

On March 29, 2002, the National Transportation Safety Board Investigator-in-Charge, Federal Aviation Administration (FAA) inspectors, and representatives of Boeing interviewed the crew. All four crew members subsequently provided written statements.

According to the captain, the crew had originally planned to practice landings at Paine Field, then stop and refuel the airplane. After the refueling, the airplane would return to Boeing Field. Estimated time en route, between the two airports, was 20 minutes.

Prior to the first flight's departure, the captain spoke, via telephone, with the maintenance manager about the status of remaining maintenance jobs to be completed before the airplane was released. (Note: The maintenance manager was seated at the avionics station for the accident flight and is hereafter referred to as the observer.) The remaining maintenance consisted of pre-oiling the engines and checking the fuel quantity.

After the telephone conversation, the observer met with the captain in his office. Shortly thereafter, the first officer for the flight joined them. The three agreed that prior to the flight, they would conduct a systems and procedures review at the airplane. The three then walked over to the airplane and met with the chief mechanic. (Note: The chief mechanic was seated at the flight engineer's station for the accident flight and is hereafter referred to as the flight engineer.) The flight engineer briefed the three other crewmembers about the maintenance work that had been performed on the airplane since its last flight. See Airplane Information for details.

The captain, first officer and observer then boarded the airplane and conducted the systems and procedures review. The review was concluded by 1100. At that time, the flight engineer reported to the captain that the pre-flight inspection had been completed, and the airplane was released for flight. The captain asked the flight engineer how much fuel was onboard, and the flight engineer reported that 425 gallons of fuel were in the main fuel tanks. Flight endurance was discussed with the given fuel quantity, which was calculated to be two hours based on the captain's knowledge of B-307 fuel consumption. The amount of fuel onboard was determined to be sufficient for the planned flight.

About 1200, the engines were started and warmed-up, and a run-up was completed with no anomalies noted. The airplane was taxied to runway 13R (13 right), and at 1224, full power was applied for takeoff. The flight was flown to Paine Field at 1,500 feet, and carburetor heat was used en route.

Upon reaching Paine Field, the captain set up for a full stop landing on runway 16R. Touchdown was about 1247. The airplane was taxied back to runway 16R, and it was decided that the captain was going to make two more take-offs and landings, then stop to have the airplane refueled.

The takeoff was made at 1251. During the initial climb-out, it was noted that the tachometer for the number three engine (right side; inboard) indicated a momentary overspeed to approximately 3,000 rpm. With no crew action, it then returned to 2,500 rpm, which was normal for takeoff. Because of the overspeed, the flight crew decided to abandon the original plan, and return to Boeing Field to investigate the problem. The return flight utilized a flight profile similar to the outbound flight.

The return flight was uneventful; however, while on approach to Boeing Field, during landing gear extension, the left main landing gear did not indicate that it was down. The approach was broken off, and the manual gear extension procedure was begun.

The manual gear extension procedure required that a section of the carpet in the cabin be pulled up to open a hatch, and someone would climb into the belly of the airplane to manually crank down the gear. The observer was assigned the task. The first attempt was unsuccessful; however, during the second attempt, the gear was fully extended with a green light indication noted. The procedure took several minutes to complete.

The airplane was then turned back toward the airport to begin another approach for landing. The airplane was about 6 miles from the runway when fuel pressure for the number three engine (right side; inboard) dropped below minimum. The boost pumps were turned on; however, fuel pressure did not recover, and the engine lost power. The low fuel pressure light then illuminated for the number four engine (right side; outboard). The captain commanded the flight engineer to switch fuel feed to another tank. The flight engineer's response was, "There is no other tank. We're out of fuel."

The captain pushed the throttles forward and called for the number three engine to be feathered. When the throttles were pushed forward, multiple engine surges occurred. Then the surging stopped, and it appeared that the remaining engines had also lost power.

The airplane was rapidly losing altitude and the captain decided to ditch in Elliott Bay. The captain called a Mayday to the tower about 1309, and touchdown on the water occurred at about 1310. After landing, the airplane remained afloat while the crew evacuated. They were quickly picked up by rescue boats. The airplane was subsequently towed to shallower water by a Seattle Police Department boat before it partially sank in the water just offshore.

The first officer's statement of the events leading up to the ditching was similar to the captain's statement. The first officer reported that during the preflight discussions, he was led to believe that the fuel onboard the airplane was 400 gallons. The first officer stated that from previous flights, the airplane's fuel consumption was about 40 gal/hour/engine. Fuel consumption for the accident flight was calculated using 50 gal/hour/engine for simplification, which equaled 2 hours of flight time.

The first officer also stated that during the preflight discussion, the observer was asked by the captain about the airplane's status. The observer replied that all that remained was to "pull the airplane out, pre-oil the engines and dip the (fuel) tanks."

The first officer subsequently conducted a walk-around inspection before boarding the airplane to ensure all panels were closed and that all was secure. The crew boarded the airplane, and the normal checklist began. The first items on the checklist were fuel, oil and hydraulics, and the response from the flight engineer was "checked and set." The engines started easily, and ran at 1,000 rpm until the oil warmed up, taking about 10 minutes. When all checks were complete, the airplane took off.

After the engine overspeed condition was detected during the takeoff from Paine Field, the captain transferred control of the airplane t