Pop Rivets

Fabric and covering. Fabric, dopes, paint and everything associated with the coverings on our planes.
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pmanton
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Pop Rivets

Post by pmanton » Wed Aug 28, 2013 12:35

I’ve been doing some research on the use of pop rivets in the .032 ribs.

Here’s Univair’s take on it. Kind of wishy washy

Thanks for your email. The ribs we have made to the later specs of the 74-79 citabria which used the fabric rivets. The same rib numbers are called out in the 7ac, 11ac and older aircraft for using the same rib numbers. Looking into the books of the 7ac and the 11 ac they call out using a 4x1/4 screw and aluminum washer. Im not sure if Champion made a change in the later years to use the rivets due to the holes for screws were easy to strip out? We use the same holes in our piper ribs also for fabric attachment since we do not offer a built up rib like the original Pipers had. I can fax or email a copy from a later model citabria parts book that shows the rivets called out if you would like, just let me know and I will get it to you asap. Sorry for the delay in contact, had to do some diggin.

I contacted Champion and here’s their answer.

Champion aircraft service letter # 85 covers this issue.
Call the parts department and they can send you a copy.
The pop rivits are for use on the models 7ECA,7GCAA,7GCBC,and 7KCAB with the 0.032-in thick ribs,if the aircraft has the 0.020 thick ribs you must use the screws and washers. Approved rivit is AD42BSLF.


I emailed them again and asked “What about the 7AC which isn’t covered by the SL?”
They answered

Paul.

To meet type design requirments use the screws and washers.

Dale.
On Tue, Aug 27, 2013 at 3:30 PM, Paul M. Anton <pmanton@tds.net> wrote:
What do I use in the case of a 7AC with .032 ribs? It isn’t listed in the service letter.


I called WagAero when I didn’t get a reply.
They answered that they had the PMA to produce the ribs—The ribs were called out for the 7AC—use the pop rivets under authority of the PMA.
I am comfortable with this. Since the FAA granted them authority to produce ribs that required pop rivets they must be used that way OR seek data to modify them for screws.
I’ll have no problem signing the wings off with the rivets.

Paul
N2426E

Paul Agaliotis
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Re: Pop Rivets

Post by Paul Agaliotis » Wed Aug 28, 2013 13:41

Paul,
I would use pop rivets on the thick ribs and screws on the thin ribs, in your case. I believe rib stitching would be the best solution, but the Genie is out of the bottle on that one. I believe the wing drawing allows Martin clips but they are a hassle to install.
Paul
Mailing Adress : Paul Agaliotis 2060 E. San Martin, San Martin,Calif. 95046

MikeB
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Re: Pop Rivets

Post by MikeB » Wed Aug 28, 2013 14:19

Service letter 85 (Bellanca) covers the installation for pop rivets. It was a bit of a hassle for me to get approval for my L16A but the fact that I replaced all ribs with the .032 thickness basically made it a no brainer. If just replacing a few ribs some have riveted a small plate under the 1/8 inch pop rivet hole and then used a 1/4x4 PK screw and washer to fasten the fabric down. Since the wings are the same I think the FAA just wanted to jerk me around a bit as the 7BCM isn't listed as a "Bellanca" but it finally went through without too much trouble eventually. I filed a 337 along with the document for 'continued airworthiness' per their instructions. I might have went to too much trouble (by filing the 337) rather than using the PMA authority and a log book entry but I had no precident to go on other than SL85. I used the Wag Aero ribs, pop rivets and the 'approved' ring shank nails to secure the ribs. I have seen a couple of Champs that used rib stitching with approval (somehow) but unsure how well it works as the Champ ribs are pretty sharp. I concure on using the PMA authority for pop rivets as it makes a lot more sense.

We just finished the annual in my L16 today and no sign of loose nails unlike the original wire nails.

Mike

pmanton
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Location: Indian Hills Airpark Salome, AZ
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Re: Pop Rivets

Post by pmanton » Wed Aug 28, 2013 17:40

I made a score :D I have all new .032 ribs to install plus 4 new spars plus new leading edges plus new wing tip bows plus new aileron bays plus new about everything. :D

So it will be pop rivets all the way.

Cheers:

Paul

MikeB
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Re: Pop Rivets

Post by MikeB » Wed Aug 28, 2013 17:51

Looks like a fun job :D .

Mike

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hangerash
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Re: Pop Rivets

Post by hangerash » Wed Aug 28, 2013 23:44

Paul,

My wings are essentially 7ECA wings with the metal spar and they had pop rivets securing the fabric. Invest in a the pneumatic rivet puller. I found one that works from Harbor Freight (surprise). It makes the installation a breeze and you get a consistent pull on the rivets.

Richard
Richard

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