DATE: 03-30-2025 TIME: 3:30 – 5:09 ~ 2:00
Today I continued with the process of preparing the trim tab servo access cover for the installation of the servo and the ability to be able to easily remove the cover. Most of the parts that I had ordered from Aircraft Spruce had arrived so I wanted to get as much done as I could.
This comprised drilling the rivet holes in the skin with a #28 drill bit so that I can fit a 6-32 machine screw through the hole instead of the A4 rivet. I bought K1000-6 (MS21047L06 Anchor Nut 6-32), and K2000-6 (One Lug Anchor MS21051L06) nutplates. I was initially going to just use the K1000 for all six fastener locations of the cover plate but decided to use the one lug K2000 nutplates in the corners. I think this worked out better.
I used the anchor nuts as templates bu inserting a machine screw into the nutplate and through the screw hole in the skin then after drilling one hole inserting a cleco and drilling the second hole.
In order to dimple the skin now, because it was already riveted to the skeleton and my rivet squeezer had a 3″ yoke, I used my swivel head riveter and this little close quarters dimple die kit from Cleveland. Worked like a charm.
I considered using the MK-319-BS rivet which is an oversized, flush, pop rivet but that meant having to drill out all of the nutplate rivet holes as well as oversizing the #40 rivet holes drilled in the skin to #33 and I just thought it would be easier to use the AN426AD3-3.5 solid flush rivet and rivet squeezer.
Well, that was true, except that I only had a 3″ yoke on my rivet squeezer so I bought the ATS Pro rivet squeezer with a 1.5″ yoke as it was cheaper than just buying the 1″ yoke for the Main Squeeze. The ATS squeezer requires more effort than the main squeeze but it works fine. So the net result was another wait for the squeezer.
Here are some snapshot of the access hole in the skin while I was in the process of prepping it. While you can’t see it in these snapshots, I tested everything I did on a scrap piece of aluminum to make sure I could do it correctly and get the result I needed.
Unfortunately the surveillance cameras I have setup didn’t take and good pics of the work so I used my cell phone during the process.