A photo would be useful

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

EM... Please provide more info... since this doesn't make sense.

EXACTLY what part number rivet are You referring to?
As IRstuff indicated, close-up photo of the rivet head with clear focus is important.
For US manufacturers, there is NO such rivet code as -.-
For US manufacturers, there is a mandatory requirement to 'impress' [depressed lettering] their distinctive company code/symbol on the rivet head, at no specified location

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

OP seems to have given up, or found the answer elsewhere, since they haven't logged in since the day after their
posting

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

Dear friends
I have seen that rivet on critical attachment point in bk-117 helicopter.
Like attaching tail gearbox to spar or first rivets that attach longerons to skin.
This rivet belongs to group of rivets like DIN LN9198. but there is not any information about head signs.
Taking photo is forbidden in our shop. but if i could, i will upload photo about subject.

E_M...

I suppose, removing 1-rivet from the shop stock-bin... for a photo of the head outside of the shop environment... then returning it to the stock-bin is not possible? We may not be able to help You...

The specification DIN LN9198 is not one I am familiar with... anyone else have a clue?

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Anyone else think E_M's closing reply is genuinely odd?

Rephrased: "Humph... Why can't tell me more about what I'm seeing on this rivet head... and I told You the specification is DIN LN9198?"

NOTE.
I have a long association with US aerospace fastening and joining... and have seen/used just about every aerospace fastener-type in existence. Your question is so short of information it has us all stumped.

When I got super-curious... and as a last-resort... Googled DIN LN9198... which is an unfamiliar European spec at best... this is an example of what I got...

https://standards.globalspec.com/std/737926/DIN%20...
https://www.google.com/search?source=univ&tbm=...

Reminds me of several old jokes and a 'truism'...

Anyone who believes in telekinesis raise my hand. Come-on, try harder.
I'm thinking of a number between 1 and 1000... what is it?

A picture is worth a thousand words.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

A bad day at the office?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

I RF'd it, as being inappropriate. Actually Will, you made the same suggestion I was thinking of.

another day in paradise, or is paradise one day closer ?

Dear Experts
I took a lot of hardship!! and prepare a photo by solidworks.
If thinking it was familiar i will be thankful to give me information about the rivet and it's material.

• https://files.engineering.com/getfile.aspx?folder=35165401-f37e-421c-a3c3-4

whilst I can't help with the head identification, I did google "LN9198" and got, from Aeroval, ...
"Part Number LN9198-3208BF is a UNIVERSAL RIVET manufactured or catalogued by Airbus Helicopters, Inc."

Forgive us (mostly in North America) for not knowing propriety Airbus rivets.

Have to checked the maintenance manuals where these rivets appear ?
Have you called Airbus help desk ?

another day in paradise, or is paradise one day closer ?

My best estimate ['WAG' = wild-ass-guess]…

The raised dot indicates alloy = 2017-T4.

The [2] bars that fade-out of both sides of the raised-dot [which I assume are more smooth/rounded than shown], are either: (A) proprietary identification markings; or (b) are defects [artifacts] from the head die-forging process.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

I have to thank every expert for giving advises.
I will probably measure the hardness of that rivet to find out the material and temper.
Most likely to be 2024-T4 (ICE-BOX).
I hope the wrath of god for the aerospace industry that use other standard than usual!! and worse than that for design poor structure .
best regards

E_M... In addition to hardness, You must also measure electrical conductivity [%IACS] to validate alloy [test on a bare-metal surface of the rivet].

Do you install these rivets 'cold' [as=is] or heat treated/quenched... installed out-of-an ice-box?

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]