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Who makes these exhaust clamp bolts? (Socata TB20)

They cost a fortune – over 100 quid last time I looked.

They are some sort of steel because they do corrode, but it could be stainless steel which (regardless of grade) will corrode at those temperatures. They are definitely not inconel because that’s what the exhaust is made of and that’s still clean after 1500hrs.

Socata P/N ZOO.N5101230295, later TB10 56015100, later TB10 56015100.

Administrator
Shoreham EGKA, United Kingdom

Metric ?

What’s stamped on the head ?

Last Edited by at 14 Jan 08:31
FAA A&P/IA
LFPN

I don’t think they are marked.

The 6mm stud suggests M6 but I must have had a reason to note down the 5.34 as the thread OD which is obviously not M6 – but that could be due to heavy corrosion. OTOH the 6mm ID of the bush (which is trivial to machine up out of say 316 stainless) does again suggest an intention to use an M6 bolt.

The nut has 12 faces (I think), not standard hex, and looks like this

It has the metal lock feature but it’s not this style

(although obviously it could be) – it is more like this

Administrator
Shoreham EGKA, United Kingdom

They definitely have markings, maybe worn off from corrosion.

I believe I have a stash of those 12 point, self locking, hi-temp nuts and probably the bolts as well – will check later this week when @ the hangar.

Last Edited by at 14 Jan 09:42
FAA A&P/IA
LFPN

Are ALL (excepting engine & accessories) the fasteners on the TB20 metric ?

FAA A&P/IA
LFPN

Are ALL (excepting engine & accessories) the fasteners on the TB20 metric ?

AFAIK yes.

These are a bit of a halfway thing. The engine is American but the exhaust is Socata, and the clamps are definitely Socata. Some pics:

But then you have things like this

where the switch is obviously NPT so they have a converter somewhere.

More details of the clamp itself here

Administrator
Shoreham EGKA, United Kingdom

The bolt heads have markings but can’t read them in the photos

FAA A&P/IA
LFPN

Yes – I can’t read them either.

But who cares? They are prob99 made by some obscure French outfit which went out of business in 2003 and what one would get on a current order would be something totally different. If I order say an engine air filter by the Socata P/N I won’t get that part; I will get a Brackett one for 1/2 the price and that will be from the Socata supply chain. Anyway nobody with a brain buys Socata parts if there is a generic equivalent (though a maintenance shop will prefer to make 25% on 100 quid than 25% on 10 quid, obviously, but that’s another story).

Administrator
Shoreham EGKA, United Kingdom

The markings on the head tell us the Manufacturer, Grade and Class, with these you will be able to source like parts.

FAA A&P/IA
LFPN

The nut looks like an NAS1804. Surely you can replace these nuts and bolts with any suitable aircraft grade AN fasteners? LAS Aerospace supply many different size AN UNF and UNC bolts in stainless steel with all metal stainless stiffnuts to match at much more reasonable prices. Do they need to be metric if you replace both the nut and the bolt at the same time?

EGTP
57 Posts
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