3 ms·

> They are likely the same exact part, just without markup for having some documentation attached to them. Why would they be the same parts? Why would their ma

> They are likely the same exact part, just without markup for having some documentation attached to them. Why would they be the same parts? Why would their manufacturer go through extensive testing if they have no incentives in doing so? Somehow people here seem to believe that “documentation” is expensive, but most of the expense doesn't come from the paperwork itself but from the things that you are required to do by these pieces of paper. And if you want to save costs, you're gonna save costs on the manufacturing process, not just on the paperwork.

charcircuit 3y ago
>Why would they be the same parts? If you are buying a replacement part you would want to buy one with the same specs as the part you are replacing. >Why would their manufacturer go through extensive testing if they have no incentives in doing so? Manufacturers will test their parts so that buyers can see if the part is usable for their needs.
- littlestymaar 3y ago
  > If you are buying a replacement part you would want to buy one with the same specs as the part you are replacing. But without the paper, you cannot know for sure if the spec is the same (you can't see the difference between aviation grade screws and regular screws with naked eyes for instance). > Manufacturers will test their parts so that buyers can see if the part is usable for their needs. Manufacturers want to sell their parts, they don't want buyers to “see if the part is usable for their needs” (if the buyer doesn't buy, that's a missed sale). I mean have you never buy anything? Sellers want you to believe their product is good so you buy it and they make money, that's how it works. And customers being disappointed by false marketing promises is routine stuff, including in the B2B sector.
sokoloff 3y ago
See the Ford/Cessna VR story here: https://news.ycombinator.com/item?id=37776842 https://news.ycombinator.com/item?id=37776842 That’s paperwork and an ink stamp as the only difference. There are other cases now where NDT is used on high-grade bolts and Heim joints. Parts coming off the same line are sold with a -M suffix (“this bolt was individually magnaflux tested and can go on an aircraft”) or not (“this part can go on a tractor”). Where no failures are ever found in NDT, I think most practical engineers would agree that the parts are physically identical.
- littlestymaar 3y ago
  > Parts coming off the same line are sold with a -M (“this bolt was individually magnaflux tested and can go on an aircraft”) or not (“this part can go on a tractor”). I think most practical engineers would agree that the parts are physically identical. Wait, of course they are identical… unless there is a defect! But that's the point of testing: when you can tolerate 1% defect then you can just sample your production line, but if your “safety demonstration”[1] relies on the fact that no screw is going to fail catastrophically under load because there's a defect, then you have to check them all. It's not “That’s paperwork and an ink stamp as the only difference”, exhaustive testing vs statistical testing. The work needed for the testing process is actual work, it's not about filling the paperwork. [1]: not sure this terminology exists in English, I'm just doing a literal translation of a nuclear Engineering concept I know in French only.
- peteradio 3y ago
  That story said it was easy enough for that particular part to have 1 line rather than 2, its not generally applicable to all parts.

charcircuit 3y ago

>Why would they be the same parts? If you are buying a replacement part you would want to buy one with the same specs as the part you are replacing. >Why would their manufacturer go through extensive testing if they have no incentives in doing so? Manufacturers will test their parts so that buyers can see if the part is usable for their needs.

littlestymaar 3y ago
> If you are buying a replacement part you would want to buy one with the same specs as the part you are replacing. But without the paper, you cannot know for sure if the spec is the same (you can't see the difference between aviation grade screws and regular screws with naked eyes for instance). > Manufacturers will test their parts so that buyers can see if the part is usable for their needs. Manufacturers want to sell their parts, they don't want buyers to “see if the part is usable for their needs” (if the buyer doesn't buy, that's a missed sale). I mean have you never buy anything? Sellers want you to believe their product is good so you buy it and they make money, that's how it works. And customers being disappointed by false marketing promises is routine stuff, including in the B2B sector.

sokoloff 3y ago

See the Ford/Cessna VR story here: https://news.ycombinator.com/item?id=37776842 https://news.ycombinator.com/item?id=37776842 That’s paperwork and an ink stamp as the only difference. There are other cases now where NDT is used on high-grade bolts and Heim joints. Parts coming off the same line are sold with a -M suffix (“this bolt was individually magnaflux tested and can go on an aircraft”) or not (“this part can go on a tractor”). Where no failures are ever found in NDT, I think most practical engineers would agree that the parts are physically identical.

littlestymaar 3y ago
> Parts coming off the same line are sold with a -M (“this bolt was individually magnaflux tested and can go on an aircraft”) or not (“this part can go on a tractor”). I think most practical engineers would agree that the parts are physically identical. Wait, of course they are identical… unless there is a defect! But that's the point of testing: when you can tolerate 1% defect then you can just sample your production line, but if your “safety demonstration”[1] relies on the fact that no screw is going to fail catastrophically under load because there's a defect, then you have to check them all. It's not “That’s paperwork and an ink stamp as the only difference”, exhaustive testing vs statistical testing. The work needed for the testing process is actual work, it's not about filling the paperwork. [1]: not sure this terminology exists in English, I'm just doing a literal translation of a nuclear Engineering concept I know in French only.
peteradio 3y ago
That story said it was easy enough for that particular part to have 1 line rather than 2, its not generally applicable to all parts.