[prkaye]

I am just bolting the aileron attach brackets on. The plans call for AN3-4A bolts and 960-10 washers. It seems to me (looking at the diagram on page 148 of the Standard Aircraft Handbook) that the grip length is too short here (quite a bit of thread inside the material being bolted together). Did anybody else notice this? Should I trust the call-out or go with a thiner 960-10L washer?

 

[f1rocket]

Generally. I treat all bolt lengths and rivet lengths in the plans as "suggestions". You are doing the right thing to check for conformance with the Standard. Pure and simple, put in a bolt that conforms.

Now on the other side, it probably isn't that big a deal if a thread or two is inside but hey, that's what the standard is there for. I usually keep an array of -3 and -4 bolts in my stock to get the proper fit.