Plus Nuts

[daxman1]

OK, here is something I have never come across before so I'm hoping someone on here has. There areas on our aircraft that we use something called a "Plus Nut". The part number I'm currently working with is S8P150. I have never worked with them in the past so I have no frame of reference on them. They seem to work like a "Mollie Bolt" that I have used to hang pictures on drywall.

Our specs do not give a requirement for fastener penetration using plus nuts. Most of the time I have seen requirements of 1.5 to 2.5 threads protrusion but here I have been informed that there is no requirement for thread protrusion with plus nuts. I find this hard to believe and have a call into the manufacturer to get their input.

Does anyone here have experience with "Plus Nuts" as to their thread protrusion requirements?

 

[WKTaylor]

daxman1... This 'PlusNut is new to me. I am pretty familiar with all-things aerospace/aeronautical fastener usage.... never heard of these...

I assume You are discussing...

http://www.enfasco.com/catalog/part/S8P150

IF the 'PlusNut' used in light duty non-structural applications in thin sheet metal and plastics [thermoplastics and FRP] they MIGHT work 'OK' if environmental protection [sealing, etc] is not an issue... and they were thoroughly tested/validated for those specific applications. Otherwise the TDS appears to identify the fastener for light duty industrial usage only.

NOTE.
OEMs/vendors typically would get very 'twitchy' if their industrial part are used in any man-rated aircraft... for any reason... some will even just say 'no comment' and 'hang-up' quickly IF they know where the conversation is heading.

NOTE.
The 'PlusNut' appears to have heritage in-common with 'RivNuts' [NAS452/NAS453 and NAS1329/1330] and 'light duty industrial blind rivets' that have 'petaling blind tails' such as... the Trifold [

https://bylerrivet.com/products/items-list.aspx?cat=485

], 'Magnatight'

https://www.afshuck.net/us/en/Products/Fasteners/Blind_Fasteners/Magna-Tite.html

and Bulb-Type blind rivets

https://bylerrivet.com/products/items-list.aspx?cat=113

NOTE.
There are other Nuts for light-weight and thin/fragile composite structure... that I would use in-lieu-of 'PlusNut's ... such as ClickBond adhesive bonded nutplates

https://www.clickbond.com/

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]

 

[berkshire]

Ok Guys ,
The plus nut is like a rivnut in its action, and is installed with a tool like a rivnut tool. They are usually Aluminum coated steel, or stainless.
Here is a table from rivnut

http://www.rivet-nut.com/assets/plusnut_catalog_specifications.pdf

They also make a pre bulb'd version that can be installed with a wrench.
B.E.

You are judged not by what you know, but by what you can do.

 

[edmeister]

additional info on this fastener (+Nut) from BOLLHOFF literature ..
> "Ideal for plastics & thin Sheetmetal
> Can be installed with inexpensive handheld tooling for kitting & consumer installation"
... thus if some simple item is to be attached to secondary structure / a complete kit can be assembled; including the installation tool, for field installation. IMHO alum rivnuts could be a substitute, but the 4x folding buckled extensions would seem to be a better security against 'spinning'. Rivnuts are notorious for spinning in thin materials. WRT thread protrusion .. last thing u want is to initiate 'nut spinning' in an application where there is no access to the other side. Imagine how difficult it would be to 'unscrew' the screw and/or drill through the fastener / and or +Nut. Again - only non-structural application / minimum quantity of threads for security. Attempting 1-2 threads extending past the end would result in a high probability for the +Nut to spin.