Not sure where this is going!

MikeB · Post by **MikeB** » Mon Apr 14, 2008 14:16

If you've been following my posts regarding wing rebuilding, you'll note I bought four new spars and am replacing all the .020 ribs with .032 ribs. Rather than fiddle around with different size ribs, and not to mention the .032 ribs come with 1/8 pop rivet holes so it's either necessary to drill a hole for the PK screw off to the side or rivet a new plate under the pop rivet hole, I decided to go with pop rivets.

I got a copy of SL 85 from Nathan and gave all my information to my AI so he could write up a form 337 for approval to use pop rivets rather than PK screws. Talking to him and the FAA guy this morning it sounds like it had to be submitted to Chicago engineering...grrrrr

.

Apparently the rub comes in as the SL 85 refers to the model 7ECA and mine is a 7BCM and the SL doesn't mention the 7AC, 7BCM, CCM ,etc. So like I said, I'm not sure where this is going. When I talked to the FAA guy before I started it didn't sound like it would be a problem.

Anyway, here I am trying to do things right and get hung up on a technicality. There really are no options here as .020 ribs are no longer available to my knowledge and beside the wings are already assembled with .032 ribs. If anyone else has experience or an approved 337 for .032 ribs and pop rivets I'd like to hear from them

Thanks
Mike Berg

Post by **joea** » Mon Apr 14, 2008 15:49

Mike,

Lets hope that Jerry M or someone else chimes in here. Maybe he has some ideas that we do not.

Joe

jerrymjr · Post by **jerrymjr** » Mon Apr 14, 2008 16:58

Good thing you sent a messege, cuz I dont prowl on this one...

Anyway, I would bet it refers to the 7ECA because thats about the point in time that the transition was made (1967). It probably looked to them that no one would be doing what you are doing (now, 40 years later).

The substantiation report for the pop rivets was model specific (for the reason above), but focused on what needed to change. Which we have covered over and over as thicker ribs.

I think the first paragraph tells the story...It says rib thickness changed and so did the screws. The last paragraph talks very generically about using the rivets. Its a matter of using common sense. Yeah, I know, asking a lot here.

So going strictly by the book, you have to be one of these models to directly use the letter with no 337. However, you should be able to call it a minor mod to use the rivets, based on the information in the letter. clear as mud? It does bring up the question about using the 0.032 ribs in the first place though. Might need to cover that too.

The key might come down to getting Chuck enough information to get it down to a level where he has authority. Without enough data, he will be forced to pass it on to Chicago ACO. If needed, you could hire a DER to get it where he can sign off on it. (actually your IA would have enough at that point.)

MikeB · Post by **MikeB** » Mon Apr 14, 2008 17:30

Thanks Jerry,
As you said it all comes down to common sense and the SL 85 is 1967.
Well, be interesting to see how this all plays out. Boy, I sure don't want to use PK screws in those nice new ribs. I sent all the information to my AI. Hopefully he'll be able to pass it on. He has no problem with it at all.

Mike Berg

MikeB · Post by **MikeB** » Wed Apr 16, 2008 12:53

Update here!
Jerry contacted the FAA on my behalf and it appears they won't be holding up certification of the 337 regarding using .032 ribs and pop rivets. So many thanks to Jerry. Great to have factory support like this on a 60+ year old plane

.

Mike Berg

Post by **joea** » Wed Apr 16, 2008 13:23

Mike,

Glad to hear it.

Just think, if they support a 60 year old airplane like this, how good will the support be on a new Champ!

Jerry, please get us at least one of the new Champs at Middletown!

Its less than 60 days away so please let get something firmed up.

You can sell airplanes at the Middletown fly-in!!

Joe A

Paul Agaliotis · Post by **Paul Agaliotis** » Wed Apr 16, 2008 14:55

Mike,
Is the intention to add the 7BCM to the Service Letter or are they just streamlining your process.
Paul

MikeB · Post by **MikeB** » Wed Apr 16, 2008 21:53

Paul, I'm just assuming they're (hopefully) going to approve my 337.

However, because .020 ribs are no long available there should be some kind of a process for using .032 ribs and pop rivets for others down the road so this doesn't need to be handled on a case by case basis.

Basically, other than emailing Jerry, I've tried to stay out of it as not to cause too much fog. While it's a fairly simple issue to me, it seems the more people that get involved the more confusing it gets so I'm going to let nature take it's course (30+ years of working in education has taught me that

),

Mike Berg

Paul Agaliotis · Post by **Paul Agaliotis** » Thu Apr 17, 2008 08:11

Mike,
I was curious about the outcome due to the fact that over the years I've seen many different 337's for the same process. There should be a way for the TC holder to add and remove effectivity in the Service Letters easier.
Paul

Post by **joea** » Thu Apr 17, 2008 08:45

Paul Agaliotis wrote:Mike,
I was curious about the outcome due to the fact that over the years I've seen many different 337's for the same process. There should be a way for the TC holder to add and remove effectivity in the Service Letters easier.
Paul

Somewhat the way that Burl has done with the ball type fuel valve that he developed for the Sedan and now is allowing to be used on the Chief and Champ?

Paul Agaliotis · Post by **Paul Agaliotis** » Thu Apr 17, 2008 09:56

Exactly Joe,
Burl, being the TC holder is able to manufacture an adapter kit for the Sedan. The installation will be handled like any other approved part.
The Champ and Chief will need their TC holders to approve the part before it can be installed in a like fashion. At this time the best the mechanic could do is use Burl's installation information as acceptable data for approval via a 337.
It would be great if ACA could approve this item per Burl's engineering data. But, I bet the engineering didn't come cheap and Burl has the right to protect his investment.
Paul