After the inspection of the elevators by DGLV, I continued to close them.
To avoid cracks near the ends of the stiffeners on the trailing edge, I decided to add some RTV on the stiffener ends and on the last rivet.
You will find plenty of into on this on vansairforce.net. It's an ongoing debate whether this still makes sense or not. Some claim that it was only a problem on earlier models and that the new bend skins on the new kits won't have the problem.
I took the decision to do it anyway. I used the RTV shown below. I got this from autozone and applied it after cleaning the surface with silicon entferner.
Applied the RTV :
Then started the next job. The rolling of the leading edges of the elevators.
This part is really fun ! You will love it, it is so exciting and so rewarding.
By the time you will be finished with the first one, you will understand the cynism in that sentence.
Rolling the leading edges is by far the worst job you have to do on the entire airplane. If you get frustrated, step away and do something else until calmed down. I'll explain later why.
I found the following on the website of Andrew. I hope he doesn't mind me repeating it here as I found it the best possible way to explain the portion in the manual "rolling the leading edges".
It’s funny. The directions say “roll and rivet the leading edges.”
Hmm.
Sounds easy.
If I were writing the directions, it would go something more like this:
“1. After spending 50 man-hours carefully protecting all of the aircraft-grade aluminum from dents, scratches, and general mistreatment, duct-tape a steel rod to the inside of the leading edges and use ALL OF YOUR MIGHT to roll that sucker around. You won’t be able to make the roll anywhere close to acceptable the first time around, so be prepared to curse and fight your way by hand squeezing the two edges together to get clecos into the holes that have been so generously provided for you. Then, rivet the two surfaces together, but only after realizing that the clamping force of the clecoes was helping everything line up, so pray that as you set the blind rivet, it will pull everything back to alignment.
2. After riveting, stand back and realize that on one of the sections, you forgot to edge-roll one edge, so there is a slight puckering between two of the rivets, but don’t worry yourself about it too much, because although it will keep you up at night, no one else will see it once the elevators are mounted to the horizontal stabilizer.
3. Stab yourself in the eye with a cleco, and then try not to bleed into the adult beverage of choice that you have now earned.”
At first, I used a big diameter iron rod. This is actually a pole for outside fences.
The diameter on this one was too large ! Use something smaller like a broomstick of a PVC tube. The PVC tube worked best for me in the end.
Another tip: don't do what I did in the picture below. Bend each part individually instead of trying to do all at once. It will not make a difference in the bends and it will be much easier.
While bending, make sure :
- to make a little bend in the edge of the outside skin before you start rolling. It's impossible to do this afterwards when both sides have the bend.
- Bend the inner part just enough.
- Overbend the outer part. This will increase the quality of the joint but will make the drilling harder.However, underbending and having to fix the open joints later is much worse... believe me. Ask me how I know.
My first attempt on the left elevator was a fiasco (disaster).
The image below shows why. The bend was bad, the edge waved. This is where I got frustrated and stepped away. (after messing it completely up by trying to use the pliers to fix the edges and by doing so making dents in the rolled skin on the other side :(((
You can see the dents on the bowed edge on the left.
I came back to the job later in the evening and decided to use another bending devide and technique for the right elevator. This time I used a PVC tube and made it just wide enough for one section.
The smaller diameter and overbending the edges made a world of difference.
The bend was not perfect and I had to work the edge at some point near the narrow end.
The middle section is the most difficult. The reason is that the radius is varying along the length but the bend radius you make with the tube stays constant. By doing that, it creates stress in the narrow end and tries to push out the edge.
Once you are satisfied with the result of the overlap, it's time to drill to #30.
This is also not as easy as it seems at first sight. At some points, the skins won't fully touch, so you need to find a way to pull them together when drilling and rivetting.
A good tip is to use gorilla-tape as in the picture below to fixate the bend in position while you remove the cleco to drill.
I was quite satisfied with the result in the end on the right elevator.
The joint is nice at most places and only 2 locations have a small imperfection of less then 1/32". On the other hand, this will be partly hidden in the end part of the horizontal stabilo so nobody is every going to see this again once the elevator is installed on the horizontal stabilo. So I'm the only one to lay awake at night about such details.
Once the leading edge was rolled and rivetted, I decided to install the rod end bearings that attach the elevator to the horizontal stabilo.
The plans call for 13/16" between the center of the bearing and the web of the spar. 13/16 = 0.8125
In place and blocked by the AN316-6 jam nut.
Same procedure on the outboard side
I will try to find some courage tomorrow to try to re-bend and fix the rolling of the left elevator.