Mounted the bottom longerons on to the bottom skin. The longeron should protrude over each end by about 1". The skin fits nicely into the little notch on the side. Started in the middle and used a 2x4 wood support underneath to drill and cleco. The skin is curved so you must keep pushing the skin into the notch as you go. Went from middle to front and then middle to rear, clecoing about every 4 or 5 holes..
Then flip over to add the Z channels around the opening and a few other parts. Z channels should get drilled/attached on each end. Flipped it back and now rerady to drill the other holes in the Z channels. UPDATED NOTE ON Z CHANNELS: Do not use the Z for the 2 short pieces that go from the edge of the access opening to the longerons....these should be L angles, otherwise there will be interference with mounting some channels to the side skins, this is an error in the Homebuilt Help videos as Jon Croke uses the Z Channel here and ends up having to correct it.
UPDATED NOTE Jan 16, 2017:
Went to install the nutplates on the bottom skin access panel and lo and behold I could not get the dimpler in to dimple the holes because the z angle support angles around the hole were riveted in place. If you want the nutplates installed properly (with countersunk rivets) you must install them before installing the z angles. I had to drill them out, then dimple the holes and the nutplates and install with 3/16 flush rivets.
This is not the way Zenith shows installing them, they do so with a domed 3/16th rivet, which IMO is just wrong because the access cover will not then sit flat and this large hole in the fuselage bottom skin is a known entry point for CO2, so the access cover should sit flat for a good seal.
