Champ 7AC wing fabric question

Hiperbiper

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May 30, 2020
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Shreveport Louisiana DTN
OK; I'm ready to cover my wings and started looking at the rib attachment spacing on my bird...
As far as I can tell the previous covers used 2.5" in the propwash area and 4.5" on the rest of the wing.
However, AC43.13 lists 3.5" outside the propwash area as the max spacing for 129 mph vne. The Polyfiber manual uses the same graph.
Two Champs here on the field also have the wider spacing...
I'm not seeing any references to covering in the Aeronca Champ Service manual either.
I am confussed...🤔 . Where is the Official Okey Dokey for the 4.5" spacing coming from?

Chris
 

Tangogawd

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Sep 13, 2020
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Alaska
If I were your IA, I'd say you are safe to go with what the manufacture did, which I'd bet is 4.5", but if you'd like, go with 3.5" as its more conservative. There is a service letter somewhere that talks about using rivets instead of screws I believe, and also talks about moving the hole 1/2" if its been oversized. so with that I'd say go with the original hole location +/- 1/2"
 

Bartman

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OK; I'm ready to cover my wings and started looking at the rib attachment spacing on my bird...
As far as I can tell the previous covers used 2.5" in the propwash area and 4.5" on the rest of the wing.
However, AC43.13 lists 3.5" outside the propwash area as the max spacing for 129 mph vne. The Polyfiber manual uses the same graph.
Two Champs here on the field also have the wider spacing...
I'm not seeing any references to covering in the Aeronca Champ Service manual either.
I am confussed...🤔 . Where is the Official Okey Dokey for the 4.5" spacing coming from?

Chris
I'd go with however the manufacturer did it unless the IA doing the sign-offs feels differently.
 

Hiperbiper

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Joined
May 30, 2020
Messages
103
Location
Shreveport Louisiana DTN
Thanks for all the replies.
It appears that indeed the factory did the 4.5" spacing and that trumps (can I still use that word?🤬 ) AC43.13.
Even though I found out Bill Pancake has an STC for either pop rivets or actual rib lacing on the old birds I'm sticking with the PK screws ( because I've got those, washers and holes in the ribs...).
Now to enlist help...

I might call the 'ol lady and ask if she'd like to come to the hangar and scr...🥳

...ASSIST...!

Chris
 

Bob Turner

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Apr 4, 2018
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1,299
A couple of hints - even though you didn't ask.
Mark each hole with a 1" pencil line. Then - and I am assuming dope or Polybrush here - coat each rib 2" wide. Let it dry. Then put your reinforcing tapes down, and put a 1" wide layer of dope/poly on the tape. Let that dry before punching for rivets or PK screws.
I have learned to love rib stitches - nice to know Pancake has an STC. I now use the palm tree/rabbit method, and am delighted with the appearance.
 

Hiperbiper

Well-known member
Joined
May 30, 2020
Messages
103
Location
Shreveport Louisiana DTN
A couple of hints - even though you didn't ask.
Mark each hole with a 1" pencil line. Then - and I am assuming dope or Polybrush here - coat each rib 2" wide. Let it dry. Then put your reinforcing tapes down, and put a 1" wide layer of dope/poly on the tape. Let that dry before punching for rivets or PK screws.
I have learned to love rib stitches - nice to know Pancake has an STC. I now use the palm tree/rabbit method, and am delighted with the appearance.
Thanks for the good advice Bob, I'll try it out!
Those videos are great! I was helping out with some classes at our local A&P skool and some of the guys just couldn't get the hang of the knots...(truth be told a few of these knuckleheads couldn't tie their shoes 😳). Anyway; I got them linked the video and suddenly the hot little blond and her rabbit/crocodile story had them rib lacing fools...
I suppose it's all about motivation. 🤪
Again, thanks.
Chris