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Bad oil canning on elevator

H

HeliCooper

Well Known Member
I've riveted the skins to the rear spars and ribs. The right skin turned out great but while riveting the left skin to the rear spar I noticed the skin starting to push up. When I finished riveting to the rear spar I noticed the oil canning. Thinking the ribs would help stiffen it up I back riveted those on. The oil canning is awful and needs to be fixed I'm just not sure the best track to take. Reorder the rear spar, ribs, top skin and hinge? Drill out the rear spar rivets and try to re rivet it and smooth the skin?

Additionally what can I do when I redo the elevator in order to make sure I do not have the same problem? I had the ribs shimmed up approximately .150 inches, I started at the inboard section on the rear spar and clecoed every other hole towards the outboard side going up the ribs when I came to them. I then riveted every hole starting from the inboard side working out.
 
HeliCooper said:
I've riveted the skins to the rear spars and ribs. The right skin turned out great but while riveting the left skin to the rear spar I noticed the skin starting to push up. When I finished riveting to the rear spar I noticed the oil canning. Thinking the ribs would help stiffen it up I back riveted those on. The oil canning is awful and needs to be fixed I'm just not sure the best track to take. Reorder the rear spar, ribs, top skin and hinge? Drill out the rear spar rivets and try to re rivet it and smooth the skin?

Additionally what can I do when I redo the elevator in order to make sure I do not have the same problem? I had the ribs shimmed up approximately .150 inches, I started at the inboard section on the rear spar and clecoed every other hole towards the outboard side going up the ribs when I came to them. I then riveted every hole starting from the inboard side working out.
Click to expand...

Update:

I removed the 39 rivets holding the skin to the rear spar. You can still feel the oil canning between the ribs. My big question now for you all is what part do I need to reorder. The skin is going to be around $80 according to Vans. They also just said it is luck of the draw on whether or not you get the oil canning which seemed odd to me. I don't know if I will have better luck putting the old skin on a new sub assembly, putting a new skin on the old rear spar, or getting everything brand new and hoping they line up better this time.

Any suggestions or advice would be helpful.

Thanks,

Jim
 
Wish I could help, I'm interested in how this turns out. Surprised no one has any thoughts....
 
Update 2:

I drilled out all 87 rivets holding the skin to the ribs and rear spar (if you need help drilling out a rivet give me a call). I reassembled working form the center of the oil canning outward. Although I still had some oil canning it was reduced. two of the ribs had cracking along the dimple so I drilled them out again. Unfortunately the dimples were now misshaped and the hole enlarged to almost a #30. I have decided to scrap the rear spar, ribs, piano hinge and skin. Some local experts believe that I should have never undone the rivets and just left the oil canning. Good learning experience. Patience is key. Hopefully my new elevator comes together without a hint of oil canning so I can feel it was money well spent.

Jim
 
Oil Canning

When I built my elevator 15 years ago this was an issue. I used very small angles between the regular stiffeners and used the 3M double stick tape. I only have a few flights since my airplane has been in the paint shop for three months, but the elevators still do not exhibit any oil canning. I cleared this fix with Van's they said "go for it." Very little added weight, but I was still a little concerned about increasing any flutter possibilities--Van's didn't seem to think it would be a problem.
Elevatorwithadditionalstiffeners.jpg
 
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