CAPE CANAVERAL, Fla. -- A problem that could have destroyed a space shuttle in flight went undetected and then unreported for eight months while NASA launched five missions and almost launched a sixth.
The problem -- cracks in one of nine fuel-line temperature sensors in Columbia -- could extend to these parts in all shuttles.
The suspect sensor first spent four months with the wrong contractor before finding its way to the correct manufacturer in January. In the meantime, the National Aeronautics and Space Administration launched Columbia, which had a replacement part, Discovery and Atlantis.
Then, after two months of analysis, the manufacturer on April 1 found a cracked weld that could have caused one of the shuttle's three main engines to explode during launch. However, the company did not notify NASA until early Tuesday, 32 hours before Columbia was scheduled to lift off from Kennedy Space Center, because it had sought a more thorough metallurgical examination of the part.
NASA, meanwhile, had launched the shuttles Atlantis and Discovery a second time.
Dan Germany, head of the shuttle office at Johnson Space Center in Houston, said yesterday that he did not fault the way RDF Corp. of Hudson, N.H., handled the situation because the seriousness of the problem was not known until the metallurgy report indicated that the 4-inch-long sensor might have cracked during normal use. "We knew then we had a problem," he said.
Tests conducted yesterday revealed cracks in two sensors taken from Discovery, which flew this month for the 12th time, and possible cracks in two others.
When shuttle managers learned of the faulty weld early Tuesday, they canceled Columbia's countdown so workers could replace allnine of the orbiter's fuel-line temperature sensors as well as two faulty computer components.
If a sensor were to break at the weld during the shuttle's 8 1/2 -minute ascent into orbit, the broken piece could be drawn down the fuel line into one of the three main engines, where it could cause a catastrophic explosion.
Mr. Germany said he would have held up the launches of Atlantis April 5 and Discovery April 28 if he had known of RDF's final report.