[adolph]

An interesting substory that is simultaneously reminiscent of the Fogbank story and how Hayek's "curious task" is much more broadly applicable:

  There is a good cautionary tale here from the Space Shuttle era. That vehicle 
  had heat resistant tiles that had to be attached to the aluminum belly of the 
  orbiter. A special cloth had been certified for wiping the aluminum clean 
  before applying the primer that securely bonded the tiles to the metal. After 
  years of uneventful use, tile engineers discovered that new replacement tiles 
  were no longer curing properly.
  
  A careful investigation revealed that the supplier of that special cloth had 
  changed the lubricant used in the machine that sews its hem. Minute amounts 
  of the lubricant were being deposited on the stitching, and enough of that 
  residue was getting on the aluminum skin to prevent the tile adhesive from 
  curing properly.

[s0rce]

In medical device manufacturing you have systems in place that your vendors have to disclose changes to their manufacturing process that hopefully can catch stuff like this before people die. I can see how minute stuff gets easily passed off as not an important change.

[duskwuff]

Especially if the real change is a couple levels separated from the problem. For instance, I can imagine a situation where the manufacturer of that "special cloth" didn't even change anything themselves, but their lubricant supplier silently changed the formula of their sewing machine oil. (Or maybe even that one of the suppliers to the lubricant company changed something - it's turtles all the way down.)

[s0rce]

Yes, you would also audit the quality system for your suppliers to confirm they are sufficiently controlling for upstream changes. In theory you can have all your ducks in a row.

[shmeeed]

"In theory" is doing a lot of heavy lifting there. ;)

Depending on the product and quantity, you can factor your purchase price level times 2-10 for every level of sub- and sub-sub-supplier you want to have audited to your "wacky spec" - which may even still sound kinda reasonable, until you realize your attack surface is basically fractal to the n-th degree. The amount of process steps and auxiliaries used in manufacturing is absolutely staggering.

Edit: I need to add this depends a lot on the sector. There's useful certificates for a lot of industries, if you choose to believe them.

[pjc50]

The "curious task" full reference from Hayek:

“The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design.”

Intended as a warning against command economies and centralized structures more generally, because the information-processing requirements are much larger than one might expect. But of course there are few things more central-planning than a space programme.

[adolph]

In this case a broader reading is an exhortation to guard against intellectual hubris. Through its various trials NASA seems like a good organization for learning from error and not accepting easy answers (except when they have to terrible results), and in this siloxane story I'm glad to see evidence of institutional curiosity that I could not have drempt up.