Why so few washers?

[kevinh]

Hi ya'll,

This is my first sonex project and now as I'm getting into building the spar I have a question:

Why do the plans not show washers under nuts? For instance, the aileron bellcranks or the WIX-W16-06 wing root attach assemblies. I thought that it was almost always good practice to include a washer underneath the nut, so that tightening the nut doesn't damage the aluminum and distribute the load. I'm okay with not using washers here, but this seems different from what I'm used to.

Kevin

[Sonex1517]

Kevin

It appears no one replied. I would check with technical support on this.

Robbie

[Bryan Cotton]

I think Tony Bingeles had a good article about this. I will see if I can look it up sometime.

[DCASonex]

If memory servers me right, Sonex does not call out washers specifically, but does call for enough to be installed to bring nut to proper position on bolt. It seemed to me that the bolt length specified was sometimes longer than needed to be (never shorter) and required 3 washers, at which point I often went to next shorter bolt length.

David A.

[NWade]

If memory servers me right, Sonex does not call out washers specifically

I'm pretty sure they always call out washers when giving the list of fasteners & qty of components for an assembly. And they definitely do show the washers on the drawings; but you have to look carefully to see them in some cases (especially underneath bolt-heads in the side-view drawings).

Note that there are a couple of locations where there are no washers because the nut is intended to help lock something in place (such as some of the components on the aileron bellcranks).

However, I agree with David that in a few cases the plans specify a bolt that was longer than appropriate and would have required 4+ washers to prevent the nut from bottoming out. In those events, I did the same thing as him and used the next-shorter bolt of the same diameter.

When in doubt, though, always contact Sonex tech support!

--Noel