Fuel leak puts Atlantis' launch on temporary hold

Friday, April 5, 2002

CAPE CANAVERAL, Fla. -- A leak of highly flammable hydrogen fuel at the launch pad forced NASA to postpone space shuttle Atlantis' liftoff Thursday for at least three days.

The fuel spewed from a broken pipe for a minute, but the white cloud dissipated and did not pose any danger, said launch director Mike Leinbach.

The pad had already had been evacuated for the hazardous fueling operation, and the shuttle was dozens of feet from the leak. The seven astronauts were hours away from boarding Atlantis and had not even begun to suit up.

"We didn't ever consider this a threat to the vehicle," Leinbach said.

Atlantis' liftoff on a space station construction mission was postponed until at least Sunday so that the leak 37 feet above the pad can be repaired.

Atlantis had been scheduled to lift off in late afternoon with the newest piece of the space station, an elaborate 44-foot girder.

An engineer spotted the leak on a screen via camera, and the fueling immediately was halted about an hour after it had begun.

It appears a weld gave way because of the shock of the cold fuel on the 16-inch-diameter aluminum pipe, Leinbach said. The pipes and their welds date to at least the 1980s, and age is believed to have contributed to the problem.

Technicians will put a clamshell-like clamp over the crack that formed in the weld. The crack is about one-fourth of an inch wide and covers almost the entire circumference of the pipe.

NASA does not intend to inspect other welds in the line, Leinbach said.

"This mobile launcher has gone through 80-some tankings and has performed perfectly fine, so we do not feel we have a generic problem with all of our welds out there," he said.

The leak was not in the plumbing that feeds liquid hydrogen into the shuttle's big external tank, but rather in a line that vents fuel vapors out of the tank to prevent a buildup of excess pressure.

The fact that the leak occurred outside the shuttle makes the repairs much easier -- and quicker. Fuel leaks grounded the shuttle fleet for months in 1990, but those leaks happened inside the spaceships.

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