Today, I drilled the passenger side door for an air vent made by Vista Vent, purchased through ACS. It required a 2.5 inch hole with four mounting holes around the outside edge. I drilled it with the door off the aircraft and supported by a piece of plywood. I also drilled the large hole from both sides. Next, I cut the hole out for the delrin latch on the pilot door. This time, I didn't install the gusset first and although still difficult, it was easier with better access. The problem riveting the countersunk rivets in place for the D7 square tube is your rivet gun doesn't fit. I added washers on top of the rivet until I could get a firm grip with my rivet gun and then pulled the rivets. I still had to file the heads down a bit due to the tight fit of the delrin.
