Tonight I installed the first of two GPS antenna. This was the GA-35 and provides GPS signal to the G3X system. The second GPS antenna provides WAAS signal to the IFR navigator.
I purchased the backing plate from Stein Air, and it was great to have to mount holes pre-cut. I could then use it as a template to locate the holes on the fuselage skin.
I started by marking out the rivet holes that will hold it onto the skin, then I drilled the rivet holes into the backing plate. Then I taped the backing plate to the fuselage and carefully measured to get it square to the airflow, and at least 12 inches from the other antenna I will be installing, while also free from interference with substructure.
With the template in position I drilled all the holes into the skin. I carefully reamed all the holes to get it as accurate as possible.
After cleaning up the holes, I dimpled the skin, countersunk the backing plate, and installed the nut plates.
Then I was able to clean primer off the inside of the skin, and rivet the backplate on. With that done, I put a bead of silicone around the edge and torqued the screws to 16 inch pounds per the spec.
