T

t4tango

Member
Hi, I'm looking for some advice regarding the repair of the vertical stabiliser on my RV-4. The VS skin(amonst other things) was damaged in a ground incident and I have just removed the skin to inspect the VS ribs. The topmost rib VS 406 has been buckled however the remainder look straight and line up with drawings, measurements etc. When I come to reskinning the structure, the Vans manual suggests drawing a centreline along the rib flanges and drilling through the skin to align with this centreline before following through with the drilling into the flange. So far so good but my flanges already have holes in from the previous skin drilling, should I carefully note the existing holes to either use them/avoid them or should I replace the ribs and be done with it. Does anyone have any tips on how this could be done?

Grateful for any input

Thanks
 
I'm not exactly sure how to best attack this but I've heard of how some individuals have used a sheet of mylar film placed over the old skin with the current rivet holes marked on the sheet. If you ensure the mylar is carefully aligned with the aft edge and top of the VS skin, it would be a simple matter to drill through those markings and reproduce your current rivet layout on your new VS skin. This is no guarantee that there won't be some misalignment, though.... Perhaps you could reskin and fasten with AN426AD4 rivets? The heads would be a little larger but drilling them up would likely eliminate any misalignment.

Best of luck....
 
vs damage

Honestly, the parts are so reasonable from Vans. I suspect that for a few dollars more you could purchase new rib and not worry about any misalignment. Trying to transfer holes from a rib onto a new (non-punched) skin may be difficult and frustrating at best. Plus you could damage a new skin attempting. As always YMMV. Tim
 
Like this

Back drill what you can with everything clamped up ( aft flanges of spar, bottom rib) then cut up the old skin and cleco it on top for the flat stuff and drill. Uncleco and open up to back drill the other curved stuff. Reskinnining gets done alot in my world. Just be sure you are doing something right, the rest of the unknowns will come to you. You can figure this out.
 
It sounds like your old skin is to damaged to use for a template. You can install the new skin over the old frame using the plywood template clamps to hold it in position. Once you have achieved the alignment your after you can draw reference lines on the inside of the skin down the spar and the ribs on both sides. Remove the template clamps. Using the reference lines line up one side and clamp to the ribs and spar on one side only (using C clamps or cleco clamps. Backdrill through from the rib side picking up the holes with a 90 deg air drill or equivelent. When done with one side un cleco, line up the marks on the other side and repeat the process. Easy Money
Ryan
 
Day

Rich

The vert stab is built in a jig to ensure no twist. If you set up the par and ribs in a jig it would be relatively straightforward back drilling through the skin. I have all the tools to do this in Coventry.

With a jig this could be done and riveted back together in a day.

If you need help with this feel free to give me a shout. Mob 07779311769.
 
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