[AR] Re: What happened to the Space Shuttle?
- From: David McMillan <skyefire@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 24 Jul 2019 13:16:45 -0500
On 7/22/2019 11:37 AM, Henry Spencer wrote:
And hoping that, e.g., none of their materials suppliers would change
their products enough to mess things up. (It's happened.)
Or that the "critical specs" on some components don't create a time
bomb for the next poor engineer. I had that happen on a job for a major
airframer, too -- they wanted to automate inserting hi-locks through the
fuselage skin into the ribs and stringers, and installing and torquing
down the nuts on the inside. The *nuts* should have been the *easy*
part -- after all, that's what wobble sockets were invented for, right?
This is a solved problem, with multiple off-the-shelf solutions in other
industries.
One *small* problem: the customer got their nuts from three
different suppliers. And only spec'd the thread size, torque, shear
strength, and *general* outer dimensions. In production, the nuts were
randomly mixed (they bought them by the barrel, almost literally). And
it turned out that each supplier made different choices for the
*non-critical* dimensions of the nuts, which in turn was just enough
difference to make it impossible to create a securely gripping wobble
socket that could reliably hold all three varieties.
Other related posts:
