So as Peter has explained the reason Trig use American hardwere is that they want to sell radios in the largest aviation market rather than selling a few bolts in the homebuild market in Europe.
Aren’t the current Honeywell/King and Avidyne transponders all re-badged Trig boxes, with a customised front panel?
Those companies would never buy a box with metric parts in it.
It speaks volumes for how little engineering talent these US companies have left in-house, but that’s a different argument.
nobody with more than 2 braincells buys an AN part from an aircraft manufacturer.
They instead look in the aircraft manufacturer’s parts catalog, find the part listed by AN or MS part number, and buy it from one of many sources like this one:
Related tangent: yesterday I received a service bulletin through the post from the ‘support organization’ for my aircraft, telling me that seat belts for my 1971-built aircraft “could no longer be rebuilt” and recommending that when required by the manufacturers 12 year overhaul cycle, I must buy new ones from their newly approved supplier. The communication was signed with two original signatures, which is bizarre in itself. It boggles the mind… Firstly I have no need overhaul my existing seat belts, they are rebuilt on condition, and secondly when I do I’ll have them rewebbed by somebody the aircraft manufacturer has probably never heard of, like these guys I can only assume the airframe manufacturer has no idea that somebody other than the original seat belt manufacturer is approved to overhaul seat belts! Similar to the custom airframe bolt thing, a weak attempt to maintain control over something long since overtaken by a competing philosophy.
(also metric v. US)
Make that Metric vs. Imperial pls
Or better still, split off that secondary matter to a separate thread.
A bit more complicate than that, there is the American standard and then the British aircraft industry had its standard hardware (AGS), I’m sure the Americans would not like the term “Imperial”.
On the whole the Metric & British stuff is a pain in the butt to work with for differing reasons, much of the metric stuff is only avalable from the aircraft manufacture but the British had a habit of not making anything with a splitpin hole, so you had to drill them yourself…….. With this can only look on with horror at the labour costs climb like a typhoon with both burners alight.
The fact of the matter is that AN, NAS & MS spec hardware is cheap, avalable worldwide and has a huge range of parts for all applications, using anything else just drives costs up if only because you mechanics require another set of tools to work metric aircraft.
I believe the threads on Jan’s 4-40 commercial screws are governed by an ANSI/ASME standard (i.e. American)
On the whole the Metric & British stuff is a pain in the butt to work with for differing reasons, much of the metric stuff is only avalable from the aircraft manufacture but the British had a habit of not making anything with a splitpin hole, so you had to drill them yourself…….. With this can only look on with horror at the labour costs climb like a typhoon with both burners alight.
That rings a bell… IIRC instead of using a split pin, De Havilland practice was to peen over the end of the bolt to stop the nut coming off. That really is a bit archaic.
Getting back to metric aviation hardware, if the Soviets, French or Germans ever did create AN-MS style aircraft hardware standard I bet somebody somewhere still has a copy… I’d like to see it, if it ever existed 
Nah the Germans never developed standards. It’s so unlike them really. They were reputed to use any bolt that happened to be available when mounting the aircraft.
Obviously the stereotypical German design approach would be to produce an intricate mechanical design, designing whatever was ‘best’ individually, unaffected by practicalities of volume production and maintenance. I can imagine that even in wartime aircraft production they may have produced the hardware individually for each application, however for very basic airframe nuts and bolts even they must have seen the practical value of a industry wide standard catalog. I’ll have to ask the local Bücker guys what they’ve found on the airframes of their German/Swiss built Jungmeisters and Czech/Spanish built Jungmanns. Now I’m curious.
My own experience with decades old post-war German aircraft is that they were AN-MS for anything requiring aircraft certified hardware, and whatever was handy for the rest. They didn’t seem to do so much of the French thing of making one-off metric airframe hardware. The newer German microlight stuff is obviously all commercial metric bolts and rod ends, control hardware etc, very little aircraft certified hardware.
Those companies would never buy a box with metric parts in it.
I highly doubt that given that most newer SMD IC packages are metric. Same goes for resistors, capacitors, etc. You simply cannot do any electronics anymore without a mix of metric and imperial parts on a single PCB.
Sure, for components. I was referring to the overall enclosure and fittings connected with that. For example, a US company would probably want metric screws used to secure the PCB to the case to be UNC, like all US avionics. But that’s pretty easy especially since the front panel is being customised.
I did incidentally wonder how the hell Airbus manages to compete with Boeing on maintenance costs, given the French aviation industry tendency to buy everything possible from French companies even if the price is 10x higher. On AOC aircraft there is a lot of lifed parts and no way around that. So it is really interesting to hear that Airbus use AN parts!
