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NTSB releases report on Stratoliner crash
Posted by bdk on Fri Feb 21, 2003 10:29:29 AM
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NTSB releases report on Stratoliner crash
- Offers detailed look at fuel emergency on historic plane
Seattle Post-Intelligencer 02/21/03
author: James Wallace
With power going out on one engine of The Boeing's Co.'s historic S-307 Stratoliner and a cockpit warning light showing low fuel pressure in another, Capt. Richard "Buzz" Nelson, a veteran Boeing test pilot, commanded the flight engineer to switch fuel feed to another tank.
"There is no other tank," the flight engineer responded. "We are out of fuel."
Moments later, Nelson radioed "mayday" and the Stratoliner, all four engines out, ditched into Elliott Bay about 50 feet from shore and in view of people eating lunch at nearby Salty's restaurant.
None of the four crew members was seriously hurt and the plane, though badly damaged, was recovered from the salt water and is now being restored for the second time.
Details of what happened during the Stratoliner's last fateful flight one year ago are in a factual report of the accident made public yesterday by the National Transportation Safety Board. The board's final report, which will include the probable cause of the crash and contributing factors, is due to be released today.
But the factual report, prepared by a safety board investigator in Seattle, provides a fascinating look at the last flight and the sudden and unexpected fuel emergency for two of Boeing's most experienced commercial jetliner test pilots.
The Stratoliner was the world's first airliner with a pressurized cabin for high-altitude flight. The one that splashed down in Elliott Bay was the only plane remaining of 10 that Boeing made for airline passenger service in the late 1930s and early 1940s. Restoration of the plane was completed in June 2001 after several years of work. The Stratoliner belonged to the Smithsonian Institution and was to have been delivered this July to the National Air and Space Museum's new Dulles airport annex outside Washington, D.C.
Based on the design of the B-17 bomber, the Stratoliner has two main fuel tanks and four auxiliary tanks. (An inboard and outboard auxiliary tank are in each wing.)
The fuel tanks were last topped off with 817 gallons on July 31, 2001, in Great Falls, Mont., as the plane made a fuel stop on a return flight from the national air show in Oshkosh, Wis., according to the NTSB factual report. The outboard auxiliary tanks were reported as empty and were not used. The main fuel tanks held a maximum of 425 gallons each. The inboard auxiliary tank fuel capacity was 212 gallons per tank.
Before the accident in March, the plane hadn't flown since Aug. 31, 2001, the NTSB report noted. Three ground-based engine runs were performed from September 2001 to February 2002, about two hours per engine, the report said.
After the Aug. 31 flight, a maintenance report noted that engine No. 3 was running rich at all power settings. The carburetor was subsequently removed and reinstalled. The mechanic noted, "Please check FF (fuel flow) on next flight."
Because it is a one-of-a-kind vintage plane, the crew was essentially writing the manual after each flight. Fuel burn had been calculated on cross-country flights to be about 40 gallons per hour per engine.
On its final flight, only the main fuel tanks were used. All four auxiliary tanks were dry.
The first officer was Michael Carriker, a veteran Boeing 737 test pilot and chief project pilot for Boeing's planned sonic cruiser.
The other two crew members for the flight were the chief mechanic, who was seated at the flight engineer's station, and the maintenance manager, who was seated at the avionics station. Both mechanics had been approved by the Federal Aviation Administration to occupy the flight engineer's station during Stratoliner operations, according to the NTSB factual report.
"According to the captain, the crew had originally planned to practice landings at Paine Field (Everett), then stop and refuel the airplane," the NTSB report said. "After the refueling, the airplane would return to Boeing Field. Estimated time between the two airports was 20 minutes."
Prior to the plane's departure from Boeing Field, Nelson spoke by phone with the maintenance manager about the status of the plane and was told remaining maintenance was preoiling of the engines and a fuel check.
After the plane was released for flight, but prior to its departure, Nelson said he asked the flight engineer how much fuel was on board. He was told about 425 gallons.
"Flight endurance was discussed," the NTSB report noted. It was determined that with two hours of flight time, based on a conservative fuel-burn estimate of 50 gallons per hour per engine, there was sufficient fuel for the planned flight.
"During interviews with the flight engineer, he stated that the fuel quantity was determined by looking at the main fuel tank gauge in the cockpit," the report said. "The flight engineer also reported that the fuel tanks had not been 'dipped' with a calibrated fuel stick," the report said.
This procedure of using a standard yardstick to measure fuel quantity was not part of the preflight inspection because the data had not been verified.
"Fuel flow calculations were also ongoing at the time of the accident," the NTSB report said.
The crew went through the usual check list of items before take off, including fuel, which was first on the list. "Checked and set," the flight engineer responded.
The Stratoliner lifted off from Boeing Field about 12:24 p.m. and flew to Paine Field, where Nelson made a full stop on the runway.
As planned, he then turned over control of the plane over to Carriker for the flight back to Boeing Field, where they were to perform at least one landing.
Before the plane left Paine Field, the flight engineer noticed that the main fuel tank gauges showed one-quarter of a tank. He did not report this to the captain.
The plane left Paine Field at 12:51 p.m. During the climb out, there was a brief power surge in engine No. 3 but it returned to normal. The subsequent landing approach to Boeing Field was broken off, however, when instruments indicated the left main gear was not down.
The gear was extended manually, but this took several minutes. The maintenance manager was assigned this task. He had to climb into the Stratoliner's belly to crank down the gear. The flight engineer left his station momentarily to help, the NTSB report said.
With the gear down, the flight engineer returned to his station and saw that the fuel gauges were indicating "zero."
About this time, 6 miles from the Boeing Field runway, engine No. 3 indicated low fuel pressure.
The first officer turned on the fuel boost pump for that engine. The flight engineer noted the low fuel pressure and then told the crew, "We don't have any fuel."
"What do you mean we don't have any fuel," the captain asked.
"The tanks are showing empty," the flight engineer replied.
Nelson then took back control of the plane and began emergency procedures.
The Stratoliner is now being restored in a hangar across from Boeing Field. It is scheduled to make a public rollout at the Museum of Flight on June 14 before it is flown to Washington, D.C., in late July.
