sizam,

The bolts on the outside of the wings which secure the wing to the vertical strut screw into blind nuts which are attached to the vertical strut. The bolts insert into aluminum studs which protrude from the wing. These studs are used during initial setup to acquire the proper wing alignment by screwing them into the wing to the correct depth. Once set, they are left alone and only used to fasten the wing to the vertical strut. The two cap bolts that fasten the top wing to the cabanes use nylon insert lock nuts.

I've had mine ever since it was first introduced and haven't had a problem with worn out attachments. Great plane which I fly every year and I do disassemble for the trip to the field.

Hope this helps.

Mike