Close horizontal stabiliser skin

The right hand top skin was rivetted ensuring the overall structure was level and free of twist. The left hand top skin was partly rivetted, and it was realised that the overall structure had acquired a bit of a twist. This was caused by something getting stuck under one of the baseboards of the leveling jig, and not rechecking with the laser level. The fix was to derivet the top left skin. The twist then relaxed, and was able to be reset. The mats under the baseboards were removed and they were clamped, ensuring all was as level as possible. For the left hand top skin, some holes were run through with the chuck reamer to clear some misalignments not greater than 0.1-0.2mm, so as to avoid some oil-canning.

In retrospect it would have been better to rivet the top side first. It was hard work to reduce/eliminate oil canning on the top side, having already rivetted the bottom side.