I noticed the " empennage control covers " on TSI's have relief holes for screw heads into the vertical stab. My covers did not have the relief holes, so there were four rivnuts on the vertical stab. that did not have screws installed. I decided to drill relief holes allowing the four screws in the vertical stab. to be installed. Installed continous grommets around holes in side of fuselage for the fuel hoses.