Fuel System Glitch Forces Scrapping of B-2 Test Flight

A malfunction in the fuel system of the B-2 stealth bomber forced Air Force officials to postpone the first test flight of the $530-million Northrop plane just as the aircraft was taxiing into takeoff position Saturday morning.

Air Force officials left unclear whether the problem was serious, but the aircraft was sent back to the hangar “in accordance with normal safety procedures,” according to a statement read by Col. Douglas Kennett, a spokesman.

The last-minute glitch will result in at least a two- to three-day postponement of the first flight, an inopportune delay that came just a day after a Senate panel voted to hold up additional B-2 funding until the plane completes its first flight tests.

The technical problem involved a low fuel pressure reading that occurred at a checkpoint on the taxiway when the four General Electric jet engines were throttled up to takeoff power. The aircraft, which is called a flying wing because it lacks a conventional fuselage, spent about 15 minutes on the runway as the two pilots fiddled with the engine power settings.

Northrop sources familiar with the plane said later that the low fuel pressure was not likely to be serious. However, it was the second time that a seemingly low-technology problem had stopped the high-technology bomber. On Thursday, the 350,000-pound plane became stuck in soft asphalt on the runway and a tow truck had to be called in.

“We err on the side of safety,” Kennett said. “That’s why we’ve postponed the flight.”

Les Daly, a Northrop spokesman, added: “It is just a delay in the flight; that is what you have when you have a flight-test program. It will be resolved and the program will continue.”

The low fuel pressure reading could have been caused by one of four problems: a faulty fuel pump, a malfunctioning fuel tank vent, a fuel tank leak or a faulty gauge or sensor that gave a misleading reading to the pilots, said one Northrop source who asked not be identified.

The fuel system has at least one fuel pump for each of the four engines and the Air Force statement did not indicate whether only one engine was affected. If more than one engine was involved, the problem could be more serious, the source said.

Boeing, a B-2 subcontractor, is responsible for building the fuel system and delivers that equipment as part of the outer wing of the aircraft, where the fuel is stored in tanks.

Especially Critical

The entire fuel system is especially critical to the B-2’s flight stability, a former test pilot said Saturday. To maintain proper balance--the so-called center of gravity--fuel is continuously pumped between tanks on the aircraft. Because the airplane lacks a conventional rear stabilizer and because it has such a short length, the balance must be closely controlled by a sophisticated computer, the Northrop source said.

The B-2’s first flight, more than 18 months behind the original program schedule and half a year behind the timetable set last December, is being closely watched in Washington. The $70-billion B-2 program has encountered increasing political opposition.

The postponement also was frustrating to 1,600 Northrop workers at Palmdale, many of whom are working 12 hours a day or more to prepare the craft for its flight.

“There are a bunch of disappointed people,” the Northrop employee said. “It is like walking out of your house in the morning and your car won’t start. All you can say is, ‘Oh jeez.’ ”

Private Plane Intrudes

The early morning flight preparations Saturday, which were watched by more than 100 reporters and photographers, were briefly interrupted when a private plane flew into the closed air space at the Northrop plant and landed on a runway while the B-2 was taxiing.

The pilot of the small plane, who had two children as passengers, was searched and led away by Los Angeles County sheriff’s deputies. The Air Force said the pilot had claimed to be lost and had been granted permission to land.