Boeing 777 has dainty feet [from comp.risks]

From:         ncm@netcom.com (Nathan Myers)
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
Date:         07 Apr 95 03:09:13 
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[I posted this in comp.risks; somebody suggested it belonged here too.]
 
I have heard recently that the new Boeing 777 jetliner, described
in recent news reports as "skating through the approval process",
has a little problem that might be interesting to RISKS readers.
 
It seems that an important part of the landing gear is too weak, and will
get "used up" (through metal fatigue), and need to be replaced annually.
While this is probably not a safety problem, it's an extra expense (frequent
inspections and replacements) and an embarrassment.
 
Unfortunately, fixing it isn't just a matter of making the part stronger; it
would then be bigger and heavier, affecting fit, balance, and nearby parts.
This sort of problem is familiar in the "shakeout period" of all previous
jetliners, but it's surprising that it showed up so late in the approval
process.  (A previous 7?7 has a nonlinearity in the landing gear linkage
that caused an oscillation when trying to close the doors; it was fixed by
an appalling hydraulic "patch" that cancels feedback during the nonlinear
portion of the cycle.)
 
How did this mistake get all the way through Boeing's legendary engineering
process?  The 777 is the first commercial Boeing to have been modeled
entirely on computer before construction.  Apparently the part is precisely
a factor of two weaker than it should have been.  Does this smell like a
structural model entry error?  I have been unable to find out more about the
source of the error, and would welcome more detailed information.
 
Maybe the RISK is in streamlining your engineering process so well, and
eliminating so many of the more common mistakes that would have caused
delays, that you are already getting final FAA approval before the booboos
that only time can reveal are noticed.  Or maybe the RISK is just that
better communications can leak word of embarrassments few would have known
about otherwise.