[sbalmos]

On DWG 11, there seem to be two rivet callouts on the main spar that I ran across that aren't really mentioned anywhere in the build steps.

The first, it looks to be a set of flush-head AD3-4 rivets on the bottom of the main spar, which would rivet the forward-most flange hole of the main ribs to the main spar, somewhat next to the tank screw holes. I am correct in thinking these holes in the main spar get countersunk and riveted before the tanks are bolted on, such that the rivets are basically under / inside the screwed-in tank skins?

Secondly, there are two flush-head AD4-6 rivets, one each above and below the K1000-4 platenuts in the main spar root. What are these rivets holding to the main spar? I can't seem to find anything connected there in the wing drawings.

Thanks!

 

[bruceh]

Yes, the AD3-4 rivets hold the forward part of the rib flange to the spar web under the tank skins. You can see them in this picture.

I see the call out on the plans for the AD3-6 rivets above and below the two nutplates. I just looked at my wings and those holes are empty! I guess I missed that callout on the drawing.

The note on the DWG 11 says to put the nutplates on the forward side and have the heads countersunk on the aft side. These extra holes probably need to be filled, although I can't imagine that they would add much if any strength to that area given the nutplate rivets are also right there.

You can see the empty holes on my spar here.

I will have to get those holes countersunk and filled with the rivets.

 

[Andrew M]

Leave empty

I am away from my project so I can't say, however those 2 AD4 flush fasteners are likely left empty for a reason. Given there location, there is no harm in leaving it alone until the wing slides in the fuselage. If it is not figured out by then, plug it. No need to do anything that might have to be undone later.

 

[sbalmos]

Thanks for the double-check Bruce.

Agreed Andrew. I'll leave them alone for now. Maybe I'll go back through the 1/3 size blueprints in the binder to see if anything is called out in the fuselage plans. Those two rivets just happened to catch my eye on DWG 11 as I was reviewing my spar for... well... open holes.

 

[mikehoover]

...

Secondly, there are two flush-head AD4-6 rivets, one each above and below the K1000-4 platenuts in the main spar root. What are these rivets holding to the main spar? I can't seem to find anything connected there in the wing drawings.

Thanks!

See DWG 16, AFT CENTER SECTION BULKHEAD ASSEMBLY REAR VIEW. Those two rivets are actually AN426AD4-14's that rivet the F-904G Center Section Vertical Bar to the wing spar web/doubler. I believe the callout on DWG 11 for a AD4-6 rivet is incorrect.