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<font size="+1"><font face="Comic Sans MS">Some good info at the end
of the article.<br>
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"</font></font>All of the large, original machined parts in the
wings of NASA 926 and 928 are made of an aluminum alloy called
7079-T6. At the time the aircraft were manufactured, “it was <em>the</em>
material—it was great stuff,” says senior WB-57 engineer Kevin
Krolczyk. “Years later, though, they found out that it has poor
stress corrosion properties—it’s highly prone to stress-corrosion
cracking.” Any tension, including the “drooping” of the wings when
the aircraft are on the ground, exacerbates the problem. “Nobody
uses it now. But we can’t [remove it from the aircraft] because the
whole [wing] structure is made of that material,” <br>
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RICHARD BARTH wrote on 10/5/2018 2:40 PM:
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<p style="font-size: 14pt; font-family: helvetica, arial,
sans-serif; color: rgb(51, 51, 51);"><a class="moz-txt-link-freetext" href="https://www.airspacemag.com/flight-today/mission-resurrected-180970371/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=20181004-daily-responsive&spMailingID=36536091&spUserID=NzQwNDU3NTY1MTkS1&spJobID=1380440527&spReportId=MTM4MDQ0MDUyNwS2">https://www.airspacemag.com/flight-today/mission-resurrected-180970371/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=20181004-daily-responsive&spMailingID=36536091&spUserID=NzQwNDU3NTY1MTkS1&spJobID=1380440527&spReportId=MTM4MDQ0MDUyNwS2</a></p>
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