Cracked hinges on space shuttle are deemed safe


CAPE CANAVERAL, Fla. -- The cracked hinges discovered last week on two of the three space shuttles do not threaten the orbiters' ability to take off and land safely, officials of the National Aeronautics and Space Administration have concluded.

Dan Germany, head of the space agency's Orbiter Projects Office in Houston, said tests performed Sunday and Monday on one shuttle's fuel-line doors indicated that the hinges continue to work properly even when the cracked parts are removed.

"There are adequate margins to safely close the doors," Mr. Germany said Monday.

The shuttle Discovery, which has cracks in three of the doors' four hinges, is tentatively scheduled to begin an eight-day mission March 9. If NASA decides to roll the space plane back to its hangar to replace the cracked parts, however, that date would slip by more than a month.

Mr. Germany said NASA managers would announce a firm launch date Friday after they complete a two-day flight-readiness review of the Discovery mission.

"We're starting to feel reasonably comfortable about the recommendation" that Discovery can fly safely despite the cracks, Mr. Germany said.

The hinges in question close twin doors on the orbiter's underside about nine minutes into flight, covering up valves that connect the main engines to the shuttle's large, external fuel tank during liftoff.

If the doors, covered with protective material, don't close to within a few thousandths of an inch of their design, heat generated during the orbiter's re-entry could damage or destroy the space plane.

To gauge the importance of the cracked parts, NASA engineers spent the weekend simulating what might happen if the parts in question were to break off entirely. Using the doors on the shuttle Columbia -- which has two cracks, both smaller than Discovery's -- they substituted a special test bolt that left the cracked pieces unattached to the rest of the hinge; when they operated the doors, Mr. Germany said, they found the doors still closed properly.

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