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Who makes these exhaust clamp bolts? (Socata TB20 exhaust clamps)

if you are going to make ur own bolt you need to have rolled thread!!!!!!

fly2000

I’m glad I don’t own an EASA certified ‘plane.
Exhaust bolts don’t need to be anything special save for a copper, locking, hex nut over a standard bolt.
I have fitted a million exhausts to Mercs and have never seen one fail. Exhaust clamps, yes, but the bolt/nut itself? Never.

Forever learning
EGTB

I don’t think there is anything “EASA certified” that’s a factor here.

If it was a US made aircraft, these would be standard AN or MS parts, which are reasonably priced – because they are standard parts, so there is competition.

Being a Socata aircraft, you have the “French problem” which is that the French are good engineers, but they love “theoretically perfect” solutions which can be very expensive for zero benefit. They then compound this by a second “French problem” which is that they buy French made stuff even if it costs 10x as much as a standard American part. In my business, electronics, 1978-present, I have found the French to be the most impenetrable place in “reasonably modern” Europe – because they buy internally, almost regardless of what it costs them. (That is gradually changing, BTW).

Socata like buying parts from obscure French companies which have never made any effort to export, and they live on “easy” business within France. Many of these don’t have a single English speaking person there, so they can’t export anyway. A French-only website is almost pointless. And when the old guy, who sat there hand-making this kind of stuff sells the business or dies of old age, you have big problems because nowadays nobody will make small batches of stuff.

To be fair, there is not a lot of this “theoretically perfect” but excessive engineering in the TB20, so in the overall maintenance costs context it isn’t a big deal. The notorious examples are the ISO (metric) thread hoses, the metric heater hoses, and some other bits.

I think some French engineer looked up the maximum EGT, got 1500F, then got a materials encyclopedia and looked up materials that melt above 1500F, and selected a bolt and a nut accordingly, and without having a wider aviation engineering expertise he sourced the first “theoretically correct” bolt he came across – for €50. Whereas somebody familiar with aviation would have opened the Aircraft Spruce catalogue and bought something out of that for $3. The commercial manager would then throw away the packaging and under their 145+21 authority would have used up €0.01’s worth of laser printer toner to print off an EASA-1 form, and jacked up the purchase price 3×. It would still be very cheap…

The over-riding problem, which you get with both US and European made aircraft, and which the other posts on this thread highlight brilliantly, is that loads of people who work in the business adopt extremely strict positions on parts substitution. I know one guy who runs a user group in the USA whose standard position is that you have to use original manufacturer’s parts. The motivation for these positions varies… but the result is that a lot of A&Ps won’t stick their neck out. In many cases this is because they cannot read long passages of text so if you held up AC43-13B in front of them their eyes just glaze over. The “adventurous” ones will want to do a Major alteration, with a 337 form, etc. I know many US based pilots and they find this all the time.

Obviously my comments above on French business practices are to a degree generalised, but in the aviation business (which is full of “interesting motivations” to maximise revenue, and full of people who don’t understand the regs anyway even if they aren’t trying to make money out of restrictive practices) it’s possible to carry these practices further than anywhere else…

Given that this is some kind of nonstandard bolt, I will probably use stainless steel bolts and K (locking oval) nuts – a far better solution than the present one. Thank you all for the suggestions

Administrator
Shoreham EGKA, United Kingdom
Regarding EASA: There is the theory and there is a reality ……… Vic
vic
EDME

If it was a US made aircraft, these would be standard AN or MS parts, which are reasonably priced – because they are standard parts, so there is competition. Being a Socata aircraft, you have the “French problem”

A friend who works for “a major French turbine engine manufacturer” would agree with your perception of French industrial practice. I’ve always liked and respected the stubborn independence of French industry (and Italian industry too – although in that case less so today than in the past). Different can be fun and enlightening, as well as inefficient

The over-riding problem, which you get with both US and European made aircraft, and which the other posts on this thread highlight brilliantly, is that loads of people who work in the business adopt extremely strict positions on parts substitution.

I guess that varies between sub-cultures. Just for fun let me list the part substitutions on a friend’s certified aircraft, to the best of my recollection. The approval details are probably a little unconventional in some areas. I’m not really in a position to say but there’s a possibility that the specification of the exhaust clamp nuts & bolts wouldn’t be a major issue by comparison.

Different engine model
Substantially modified cowling
Different propeller and spinner
Different exhaust stacks and heat muffs
Different gascolator
Different fuel tank installation that completely changes the wing structure.
Different instrument panel, all instruments and structural interface
Modified foot controls and lowered floor
Different wheel fairings
Different wheel brakes, master cylinders and parking brake
Different seats and mounting attachments
Different seat belts and mounting attachments
Extended baggage compartment
Different tail wheel and lengthened actuation arms
AGM battery and different battery box
Enlarged elevator trim tab
Vortex generators on wing
Gap seals on ailerons

Maybe when he dies many years from now, they’ll bury the plane with him. I have a feeling my A&P IA wouldn’t sign it off, but it actually flies very nicely.

I also know a guy who (entirely legally) built an entire Great Lakes biplane around a data plate and a logbook.

Last Edited by Silvaire at 16 Jan 00:15

http://www.alcoa.com/locations/alcoa_location/en/home.asp?code=450

most likely mfg place for the locknut for OE used to be called SIMMONS

fly2000

Yes – Simmonds, now owned by Alcoa too. Page 9 here, bottom left, is the nut.

Many thanks.

Yet another example of a French business, supplying Socata, and now US-owned. Most of the o-rings used by Socata are Le Bozec or Le Joint Francais Bezons, now owned by Trelleborg. One can find the exact parts OK but buying them is complicated unless you want say 100.

Administrator
Shoreham EGKA, United Kingdom

I have received from LAS Aerospace a 10-32 and a 1/4" bolt and the K style nut.

One will need the actual exhaust clamp to see if the 1/4" one is too big to fit. If it is too big, a 6mm one will be needed.

BTW the ARP products, which look very nice, won’t ship USA to UK. They have some distributors in Europe who I have emailed.

Administrator
Shoreham EGKA, United Kingdom

Let me know if I can help (in case you want something from ARP)

if u go imp. or M6 just make sure k nut is high temp (it does not matter 6 or 12 point) and i can highly recommend the Bostik anti seeze as it makes a hell of a differance. on f1 engines only this can be used

fly2000
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