3 ms·

These were the days when the British had their own screws (from a continental European perspective). People buying a Landrover on the continent also needed to b

These were the days when the British had their own screws (from a continental European perspective). People buying a Landrover on the continent also needed to buy a set of suitable wrenches. I guess the same holds for America. Not sure whether American screws would be the same as British ones or whether they would differ like the volume of a gallon. With global manufacturing these days, Japanese cars everywhere, German cars in America, how many screw standards are still in use? When did it change, if it did?

implements 6y ago
My father’s toolkit had metric, AF and Whitworth spanners.
- usr1106 6y ago
  Thanks, that gives the right search term https://en.m.wikipedia.org/wiki/British_Standard_Whitworth https://en.m.wikipedia.org/wiki/British_Standard_Whitworth
usr1106 6y ago
In airplane terms, does a Boeing, an Airbus, a Fokker and a BAe/Avro all use the same screws?
- usr1106 6y ago
  Not an answer to the question, but they are all likely to use different screws than what we home mechanics are used to: https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread > Superfine pitch metric threads are [...] commonly used in the aviation manufacturing industry.
- t0mas88 6y ago
  Airplanes operated for passenger transport are on a very controlled maintenance program. Almost all parts are numbered and tracked, including their age, flight hours and cycles (basically number of flights). You cannot replace even a bolt with another that isn't according to the same manufacturer spec and tracked in the same manner. So some screws could be the same spec, but in general you don't just pick one out of a bucket and screw it in.
  - throw0101a 6y ago
    > Almost all parts are numbered and tracked Airplanes are basically several thousand parts flying in formation.
- benhurmarcel 6y ago
  Even non-US aircraft use a lot of imperial fasteners (and pipes). This is mainly due to inertia. Since both maintenance shops and suppliers are already equipped.
  - iguy 6y ago
    I thought this wasn't just inertia, but required for US licensing. To much grumbling from Airbus.
overkill28 6y ago
That may be true but it's not relevant to this accident. It was a British made plane using British standard screws. The mechanic just used the wrong size bolt from the same standard. It's not like he was trying to find a metric equivalent to an imperial size or vice versa.
- xattt 6y ago
  According to the wiki, one of the recommendations from investigating body was that aircraft maintenance crews wear corrective lenses. Reading between the lines, it suggests that the tech didn’t either see the proper screw size or didn’t want to cross-reference with documentation because they couldn’t see the text.
  - kps 6y ago
    The article says #8-32 bolts were put in #10-32 holes, which is odd, because they shouldn't mesh at all (OD 0.164 vs ID 0.173). (M5×0.8 on the other hand is just pure evil NIH.)
    - 29083011397778 6y ago
      They needn't mesh if nuts were used on the inside though :)
benhurmarcel 6y ago
> how many screw standards are still in use? Basically 2: metric and imperial. It's quite common for shops to have both.
- usr1106 6y ago
  Depends on where and what kind of shop. In Europe it's all metric. Unless you are in a very special field, maybe aviation or Harley repair shop?
- lostlogin 6y ago
  There is still plenty of scope for tears. I had a Shimano internal hub gearing system on a bike. It had a bolt and nut with a thread that was unusually tight. More threads per mm. It was very easy to strip and I did it numerous times. Every second time I ordered new ones the wrong ones came and I’d strip them too. Internal hub gearing is amazing, but comes with intense pain.
  - usr1106 6y ago
    The metric standard distinguishes 3 thread pitches: regular, fine, and superfine. So even if you say it's the same standard, not everything of the same size matches. I also have Shimano internal hub. It's claimed spare parts are impossible to get. Of course just a screw might be different. When it broke it was replaced as a whole, luckily on warranty.
nickt 6y ago
If you want to delve into that particular rathole, I recommend Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook. More than you ever need to know about the subject. https://www.goodreads.com/book/show/710357.Carroll_Smith_s_Nuts_Bolts_Fasteners_and_Plumbing_Handbook https://www.goodreads.com/book/show/710357.Carroll_Smith_s_N...
esaym 6y ago
My memory is fuzzy (used to do sheet metal repair for L3 and Boeing), but I'm pretty sure the FAA requires nearly everything to be "American". This means pilots must speak English and all aircraft hardware is of the AN (army-navy) or NAS (National Aerospace Standard) standard. Hardware is always in English units (inches). In this case, the #8 screw (5/32") was used in place of a #10 (3/16") screw. Side by side, the size difference is obvious. Trying to judge the screw size by looking at the hole is not so obvious and a #8 screw will sort of cross-thread into a #10 hole because aircraft female threads are "interference fit" by (at least) about .001" so screws and bolts won't vibrate loose. I've made the mistake before but if you are paying attention, you'll know you got the wrong screw just by how sloppy it goes into the hole. That and #8 screws are only used on mostly non-critical stuff. If you were to take every screw,rivet, and bolt on a plane, 90% would probably be 3/16" in diameter.
bliss 6y ago
My brother in law works in aerospace, he worked on a project which involved a mars mission - the catastrophic error was that part of the software worked in metric and part of it worked in imperial measures. Each independantly worked in factory testing, but together the imperial readings threw the metric system (it was just a number) - or vice versa - no one caught the error
- bliss 6y ago
  This is the one - http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/ http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/
- intricatedetail 6y ago
  How something like this is even possible?
  - bliss 6y ago
    Assumption
    - intricatedetail 6y ago
      Such an ominous word. Actually been there many times.

implements 6y ago

My father’s toolkit had metric, AF and Whitworth spanners.

usr1106 6y ago
Thanks, that gives the right search term https://en.m.wikipedia.org/wiki/British_Standard_Whitworth https://en.m.wikipedia.org/wiki/British_Standard_Whitworth

usr1106 6y ago

In airplane terms, does a Boeing, an Airbus, a Fokker and a BAe/Avro all use the same screws?

usr1106 6y ago
Not an answer to the question, but they are all likely to use different screws than what we home mechanics are used to: https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread > Superfine pitch metric threads are [...] commonly used in the aviation manufacturing industry.
t0mas88 6y ago
Airplanes operated for passenger transport are on a very controlled maintenance program. Almost all parts are numbered and tracked, including their age, flight hours and cycles (basically number of flights). You cannot replace even a bolt with another that isn't according to the same manufacturer spec and tracked in the same manner. So some screws could be the same spec, but in general you don't just pick one out of a bucket and screw it in.
- throw0101a 6y ago
  > Almost all parts are numbered and tracked Airplanes are basically several thousand parts flying in formation.
benhurmarcel 6y ago
Even non-US aircraft use a lot of imperial fasteners (and pipes). This is mainly due to inertia. Since both maintenance shops and suppliers are already equipped.
- iguy 6y ago
  I thought this wasn't just inertia, but required for US licensing. To much grumbling from Airbus.

overkill28 6y ago

That may be true but it's not relevant to this accident. It was a British made plane using British standard screws. The mechanic just used the wrong size bolt from the same standard. It's not like he was trying to find a metric equivalent to an imperial size or vice versa.

xattt 6y ago
According to the wiki, one of the recommendations from investigating body was that aircraft maintenance crews wear corrective lenses. Reading between the lines, it suggests that the tech didn’t either see the proper screw size or didn’t want to cross-reference with documentation because they couldn’t see the text.
- kps 6y ago
  The article says #8-32 bolts were put in #10-32 holes, which is odd, because they shouldn't mesh at all (OD 0.164 vs ID 0.173). (M5×0.8 on the other hand is just pure evil NIH.)
  - 29083011397778 6y ago
    They needn't mesh if nuts were used on the inside though :)

benhurmarcel 6y ago

> how many screw standards are still in use? Basically 2: metric and imperial. It's quite common for shops to have both.

usr1106 6y ago
Depends on where and what kind of shop. In Europe it's all metric. Unless you are in a very special field, maybe aviation or Harley repair shop?
lostlogin 6y ago
There is still plenty of scope for tears. I had a Shimano internal hub gearing system on a bike. It had a bolt and nut with a thread that was unusually tight. More threads per mm. It was very easy to strip and I did it numerous times. Every second time I ordered new ones the wrong ones came and I’d strip them too. Internal hub gearing is amazing, but comes with intense pain.
- usr1106 6y ago
  The metric standard distinguishes 3 thread pitches: regular, fine, and superfine. So even if you say it's the same standard, not everything of the same size matches. I also have Shimano internal hub. It's claimed spare parts are impossible to get. Of course just a screw might be different. When it broke it was replaced as a whole, luckily on warranty.

nickt 6y ago

If you want to delve into that particular rathole, I recommend Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook. More than you ever need to know about the subject. https://www.goodreads.com/book/show/710357.Carroll_Smith_s_Nuts_Bolts_Fasteners_and_Plumbing_Handbook https://www.goodreads.com/book/show/710357.Carroll_Smith_s_N...

esaym 6y ago

My memory is fuzzy (used to do sheet metal repair for L3 and Boeing), but I'm pretty sure the FAA requires nearly everything to be "American". This means pilots must speak English and all aircraft hardware is of the AN (army-navy) or NAS (National Aerospace Standard) standard. Hardware is always in English units (inches). In this case, the #8 screw (5/32") was used in place of a #10 (3/16") screw. Side by side, the size difference is obvious. Trying to judge the screw size by looking at the hole is not so obvious and a #8 screw will sort of cross-thread into a #10 hole because aircraft female threads are "interference fit" by (at least) about .001" so screws and bolts won't vibrate loose. I've made the mistake before but if you are paying attention, you'll know you got the wrong screw just by how sloppy it goes into the hole. That and #8 screws are only used on mostly non-critical stuff. If you were to take every screw,rivet, and bolt on a plane, 90% would probably be 3/16" in diameter.

bliss 6y ago

My brother in law works in aerospace, he worked on a project which involved a mars mission - the catastrophic error was that part of the software worked in metric and part of it worked in imperial measures. Each independantly worked in factory testing, but together the imperial readings threw the metric system (it was just a number) - or vice versa - no one caught the error

bliss 6y ago
This is the one - http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/ http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/
intricatedetail 6y ago
How something like this is even possible?
- bliss 6y ago
  Assumption
  - intricatedetail 6y ago
    Such an ominous word. Actually been there many times.