Metric Fastener Part Numbers 1

[billtati]

I work for an aerospace, defense electronics manufacturer. We work with primarily with Imperial/English fasteners (2-56, 4-40, etc.) and due to our industry, we always reference MS or NAS part numbers (MS51957, NAS620, etc.). I would like to know if metric fasteners are detailed in a similar fashion. ANSI standards are not sufficient, as they only specify the shape, not material, finish, testing methods, etc. as the appropriate Mil- or NAS standards do.

 

[alexit]

For aviation and aerospace typically use the DIN/ISO standard LN9163 specification. Used like LN9163-M10x1-4H5H, this states min strenght, hardness, yield points, etc. then size/pitch and fit.

A source I use is:

http://www.mdmetric.com/fastindx/inxtst.htm

They have a page linked there (T44) with full reference threads.

 

[yates]

EN standards refer to metric fasteners. Also DIN or LN (aerospace); In the US of course, AIA publish NA specs for metric fasteners (equivalent to NAS, but metric MJ threads)

 

[billtati]

Thank you alexit and yates. Of course, right after I posted this question my constant searching got me the correct info. I believe I have found what I was looking for in AIA NA standards. Strangely enough I had to search on exactly the opposite of what I wanted; MS51957 imperial screws, to find a GSFC site that listed the appropriate metric numbers. For everyone's info the following are some relevant standards: NA0068 - Metric Pan Head Screw, NA0069 - Metric Socket Head Screw, NA0070 - Metric 100° Flat Head Screw. This info gives me some answers and leads me to other relevant docs.

 

[drawoh]

billtati,

I have a similar problem trying to identify metric screws by part number for use in aircraft. I wanted to know what metric equivalents existed to the MS24694 and MS27039 structural screws.

I went searching for maintenance information on Airbuses. Those have got to contain metric fasteners. Reality is that they contain at least some inch size fasteners. The metric stuff seems to be ordered to Airbus standards, rather than to some ISO, DIN, or EU standard.

Metric pan head machine screws are a pain, because very few catalogues and standards seem to describe what I get when I order one. Our metric pan heads conform closely to what is described in my Gould Fasteners catalogue as a "raised, recessed cheese head" machine screw, as per DIN7985.

The Barnhill Bolt company at

http://www.barnhillbolt.com/

quotes similar accurate dimensions for phillips pan head screws conforming to ISO7045.

I am not aware of a metric equivalent to the aircract structural screws, although I would love to be set straight.

JHG

 

[billtati]

The metric pan head screw I referenced (NA0068) does indeed look like an Imperial/English cheese head. Take a look at this Goddard Space Flight Center (GSFC) site for some more info on this:

http://supply.gsfc.nasa.gov/fasteners/met_inv.htm

Does the AIA not have metric structural screws?

 

[yates]

Drawoh,
Airbus do not use any metric fasteners. They use exclusively inch threads. As already stated, metric aerospace fasteners are defined in NA (AIA) specs. in the US or in EN (AECMA) specs in Europe. See

http://www.aecma.org

for a link to qualified manufacturers for EN screws, which will then lead to their catalogues.

 

[CoryPad]

yates,

That seems like an extreme statement. Are there zero M/MJ threads on an Airbus plane? What about other non-US manufacturers like Embraer or Bombardier?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[yates]

Embraer and Bombardier have also settled for inch-thread fasteners. I did not say there were no metric fasteners on an Airbus plane, I said Airbus (as an airframe manufacturer and assembler) do not specify metric fasteners. There may well be some non-structural metric fasteners on bought-in proprietary articles such as electronics. All engine, landing gear, climate & pressure control and flight control hardware is inch, on top of the structural.

 

[billtati]

GSFC lists the following type of part numbers for metric washers; 722-95-029-xxx-x or 722-95-030-xxx-x (the x's represent variable info). Does anyone know what spec covers these part numbers?

Also, they list the preferred washer type as NA0034 which is a nut with "extended washer" a kind of integral nut/washer. Does anyone know the NA spec for standard hex and small pattern nuts (non-structural)?

Thanks.