NASA Documents Cite Wing ‘Burn-Through’ Risk, Aviation Week & Space Technology Reports

NASA documents as far
back as 1988 show that wing roughness, similar to that associated with
the shuttle Columbia’s left wing, could result in catastrophic
burn-through when combined with wing impact damage like that being
investigated in the reentry accident, Aviation Week & Space Technology
reports in its February 24 issue.

Shuttle project office documents obtained by AW&ST spell out how
wing gouge damage near the landing gear wheel well or wing leading
edge, could combine with Columbia-type wing roughness in a “fatal
combination” that would spike reentry temperatures to nearly 1,000
deg. higher than allowable at the site of the debris strike.

The AW&ST report displays a 1988 NASA document illustrating what
could happen to a wing gouge at the identical location where similar
damage is believed to have occurred during Columbia’s launch January
16.

A gouge at that location, in connection with aerodynamic wing
roughness characteristics, could results in “massive shrinkage” or
“melting” of wing thermal protection tiles and “exposure of the
aluminum wing structure” to temperatures in excess of its melting
point, the document says.

The former chief of the NASA Astronaut Office, Robert L. (Hoot)
Gibson who has piloted five space shuttle missions, told Aviation Week
that he was “ignored and disregarded” by the shuttle engineering
community when a year after the initial thermal assessment, he coupled
serious reentry tile damage that had occurred on an earlier mission to
the Columbia wing roughness issue. “I was never quite satisfied that
we had exhausted everything that maybe we should have looked at,”
Gibson said.

AW&ST also reveals a new set of e-mails exchanged between
engineers at the NASA Langley Research Center in Hampton, Va., while
Columbia was still in orbit. The new e-mails express elevated flight
safety concerns in spite of a Boeing analysis that showed there should
be no danger from debris that may have fallen from the Lockheed Martin
external tank.

“One of the bigger concerns is that the ‘gouge’ may cross the main
landing gear door thermal barrier and permit a breach there. No way to
know of course,” Langley engineer Robert Daugherty wrote to fellow
engineer Mark Shuart on January 29, AW&ST said.

The magazine quotes the engineer’s message as saying, “We can’t
imagine why getting information is being ‘treated like the plague’.
Apparently the thermal folks have used words like they think things
are ‘survivable’ but ‘marginal'”, Daugherty wrote, adding, “I imagine
this is the last we will hear of this.” Two days later Columbia and
her crew were lost.

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EDITORS NOTE: Full text of the Aviation Week & Space Technology
article and related charts, as well as interviews providing analysis,
are available.