6.2 Position FC1, the most inboard block, with the parallel face to the spar, the outboard flush with the top of the wing surface and the inboard equidistant from the top and bottom of the CS spar.

Note that FC4/5 has been leveled at WL 17.4 so we are fitting to that point considering relative to the CS spar position and centered on it.

6.3 Note a wedge shaped gap at the wing join that also may have a twist.

6.4 Sand out the twist (pic1) so that FC1 can sit flush or within a very small gap that glue might fill. Note that the inboard edge may be just shy of its position. We will add a small amount to the inboard side of FC1 later to compensate.

6.5 Check and recheck measurements and positions.

6.6 Once happy ensure FC1 can be removed and replaced easily, exactly in position (pic3). This will take a lot of blocks and gaffer tape and patience.

6.7 Do a trial glue. Consider nails (I use pins) to maintain the position. Weights are handy too.

Trim FC1

Go for a fit

Trial fit