Wing tip screws for the SS.

[inzersv]

I would like to use flush, countersunk machine screws for the wing tips instead of the AN526 that came with the kit. What has others used instead of the kit machine screws? I don't know what I am looking for to exchange and still use the kit nut plates. Thanks a bunch.

[jrevens]

This is what I'm doing on mine, Stan... I'm using 8-32 AN 509 screws with Tinnerman formed washers. You can decrease the diameter of the washer if you have to. I bonded them to the fiberglass with Hysol. I'll paint the tips, & just mask off the contact area between the screw heads & the washers.

[inzersv]

Thanks John, I hadn't thought of doing that. Are you still using the supplied nut plates?

[jrevens]

Yes, still using the supplied nut plates. I added a couple of thin layers of fiberglass to those edges of both ribs, as they were too thin & uneven in thickness. You can just countersink the fiberglass for the screws if you want, but I don't especially like that structurally because of the over-sized hole on the fiberglass & the close edge-hole clearance. The bonded-on washers distribute the load & make for a no-wear situation. The AN509 screws are a structural screw & probably overkill for this. I might just use some 100 deg. s.s. ones instead since I have some of those. Aircraft Spruce carries all that stuff, & if you go to Oshkosh, you can find it at any number of vendors in the fly market also.