NASM1312-13 shear double-shear test fixture design

[engamopar]

I'm looking at sheet 4 of NASM1312-13 [REV 2] and it indicates the height of the fixture from the bottom of the fork to the top of the BLADE is to be "4 "S" MAX".
This makes for very thin test equipment. Is it possible this should be "4*[dia]D", "4"T"", or "4 "W" MAX"? anyone have any experience with this?
Thanx in advance.

 

[CoryPad]

The 4S requirement has been around for decades. It does not result in thin fixtures. Take a look here:

http://www.instron.us/wa/solutions/NASM_1312_13_Fastener_Double_Shear.aspx

 

[engamopar]

Thanks for the feedback, Corey but I must be missing something. I went to the link you provided. I don't see that the item pictured is even close to complying witht the 4"S"MAX requirement. In NASM1312-13, they show this dimension as being from the top of the BLADE to the bottom surface of the FORK. The "S" dimension, for all practical purposes, is the RADIUS of the fastener's diameter. Let's just for the sake of discussion say that the photo in the link's picture is of a 3/8" diameter bolt. That would mean that the 4"S" diatance would be 12/16" or 3/4" MAX! The shear fixture pictured is perhaps 3-1/2 to 4" from the top of the BLADE to the bottom surface of the FORK - about 7X the MAX limit.
What is it that I am misconstruing here, because I am not the only one here who has remarked about how small that distaance really is???
Thanks for the prompt response. What say ye next?

 

[CoryPad]

I had not noticed the 4S dimension before. The images in the current NASM1312-13 standard and older MIL-STD-1312-13 standard do not show parts with those proportions, and manufacturers like Instron and Wyoming Test Fixtures do not produce parts with those dimensions.

Please submit your question to AIA at the link below and share their answer on this post.

http://www.aia-aerospace.org/national_aerospace_standards/standards_feedback/

 

[engamopar]

Thanks, CoryPad, for the lead. I have contacted AIA and am awaiting their repsonse.