Today I worked on adding the two aft top skins to the fuselage. This including wrking on the J-channels to make sure they were the correct length. The aft top skin was already clecoed in place, so it was pretty easy to drill the rivet holes to size. Part of the process of sizing and preparing the J-channels is marking a center-line. This makes drilling the rivet line easier and more accurate. The next skin forward was a little more difficult. As the skin is flat when it is shipped it takes a little effort to fit the skin over the fuselage. I have found if I am having to force anything, I am doing something wrong. This skin did not fit. I tried and tried and found myself getting ready to force it.
After a little review, some investigation and a head scratching; it became apparent that one of the J-Channels was just a little long. This forced a bulkhead to move a couple about a 1/16th and nothing fit. After taking the channel out, re-sizing it and putting everything back together the skin fit just fine.
