Initial Prep (Debur, Trim, Drill, and Cut)
8/29/2021 – 2.7 hours
8/30/2021 – 1.5 hours
The final two parts in the empennage kit crate are the two top side skins for the aft fuselage. They are also the largest parts in the crate, and needed some work to clean up the holes and edges. The side skins don't have any tabs or tight corners, but the edges are very long with lots of burrs and tool marks. The curved sections at the forward end of the skins have the highest concentration of tool marks, which takes time to smooth down.
[Hole and Edge Deburring Tools]
Final Prep (Dimple, Countersink, and Shape)
9/5/2021 – 0.7 hours
9/6/2021 – 3.0 hours
The plans don't specify putting an edge break in the top side skins, but I decided to put a break on the bottom edge after I reviewed the installation of the side skins and how the aft fuselage joins the forward fuselage. The break is very slight, but should help the skins fit tightly where they overlap the bottom skins and eventually the forward fuselage. I did not break the forward, top, or aft edges since they do not overlap other skins.
Dimpling the top skins is a little tricky. The skins are large and have complex curves, and they are a difficult to handle. I started the dimpling procedure with the 22” C-Frame on my work bench, but the bench limited my ability to maneuver the skins into place to dimple them properly. I moved the C-Frame to the driveway to give me some extra space for the dimpling operation. I also found one hole that I don't believe should be dimpled, but isn't marked “Do Not Dimple” on the plans. The most aft and bottom #30 hole, which is labeled “Do Not Rivet” lies above a nutplate screw hole that is not dimpled. I have contacted Van's tech support to confirm that this hole should not be dimpled, and they replied that the empennage fairing will be countersunk for the flush screw and the hole doesn't need to be dimpled.
[Edge Forming Tool (Vise Grip Style), 22” C-Frame with #40 Reduced Diameter, #30, and #40 Standard Diameter Dimple Dies, Pneumatic Squeezer with #40 Reduced Diameter Dimple Die]
Prime
8/31/2021 – 1.0 hours
9/7/2021 – 1.4 hours
9/8/2021 – 0.9 hours
9/9/2021 – 0.5 hours
Priming all of the pieces for this sheet followed my now-standard process of scrubbing and scuffing the parts with cleanser and a Scotchbrite pad followed by a thorough cleaning rinse. I go back to the final preparation items like dimpling after the part is cleaned, and then degrease the parts just prior to priming. One new step this time was sanding the first primer coat and then applying a second light coat of primer. I wasn't happy with the first coat, because it was very uneven and rough with several dusty-looking clumps. I assume the clumps were a result of priming outside on a humid day. I sanded the primer with a maroon Scotch Brite pad to smooth it out, and I was surprised at how well it covered even after the sanding. I cleaned off the primer dust, did a final cleaning with the degreaser, and then put a second very light coat of primer on to fill in the low spots. The end result was really good, and I will probably continue the prime-sand-prime process on other large parts.
[Grey and Maroon Scotch Brite Pads, Bon-Ami Cleanser, Dupli-Color Degreaser, Dupli-Color Self-Etching Automotive Primer (Green – Rattle Can)]