Space Shuttle Has 2 Defective Seals, NASA Says

For the second time in a few months, defective engine seals have turned up on a space shuttle instead of in the trash where they belong, NASA said Wednesday.

Two seals that should have been thrown away are apparently in one of Atlantis’ main engines. As a result, NASA will replace that engine before the shuttle blasts off with supplies for the international space station next month.

Chief engineer Len Worlund said the flawed seals are probably safe to fly, but as a precaution they will be removed.

The work is not expected to delay Atlantis’ launch, targeted for around April 17.

“Since we know that . . . there’s a high probability that there is a defect in that part . . . we think it’s prudent for us to go off and take those out,” he said.

The problem with the seals arose in late January, when NASA discovered that a rejected seal ended up in an engine that helped propel Discovery to orbit in December.

The defective seal had, in fact, flown on three space shuttle launches, but it went unnoticed until the nickel plating separated in one spot and was rubbed by turbine blades. The damage occurred during Discovery’s liftoff on the Hubble Space Telescope repair mission.

The seals--made of 6-inch segments in the main engine fuel turbo pumps--help direct hot gas into the turbine blades to increase performance. If a seal should fail, the engine could shut down, forcing an emergency landing.

NASA proceeded with Endeavour’s launch in February, even though engineers could not verify that all its seals were certified for flight.

It was in the course of verifying about 100 seal segments that NASA discovered the problem with two aboard Atlantis, Worlund said.

All the other pieces were found to be good, including those that flew on Endeavour last month.

Records showed that the seal manufacturer had scrapped two pieces in the late 1980s because of a defect in the metal.

To Worlund and everyone’s else’s amazement, the two junked seals segments were still around. But they checked out fine, which meant that the bad pieces were sent to NASA as flight units, Worlund said.

The paperwork showed those two pieces to be on Atlantis.