is cotton rib stitching legal

[wayne turner]

my question is is cotton stitching in a polyester covered wing legal?it just became a issue with a bc-12 d that Im looking at,thanks wayne

[ROllerton]

Re: is cotton rib stitching legal

Well let me take a stab at it.

The installation of the fabric has to be done in accordance with the process and procedure that it was certified with. I doubt that the process would specify cotton thread for stiching as it would not (in theory) have the same life as the covering. If the stiching let go in flight the fabric woudl balloon off the wings and destroy lift. You need to take care of your lift. If you stick to the letter of the law, its probably not airworthy in that condition.

It was common practice at one time to use cotton tapes on poly fabric as some thought they would "stick" better. As you can guess the cotton tapes aged differently than the poly, and usually had to be replaced earlier than desired.

Somehow the idea that you could take a system, for instance Stitts, and mix and match it with parts from another and end up with your own secret recipie for covering and painting an airplane became wide spread. Using different types of glue was another bad idea. Today its not considered a good practice to mix and match.

If it was me looking at that airplane, I would budget to recover the wings and get some adjustment to the price. Or walk.

There are much smarter folks than me here on the forum that can add a lot to this, and hopefully correct my rash statements!

[3Dreaming]

Re: is cotton rib stitching legal

I saw this question in an other post as well. How is it being decided that the cord is cotton? In the other post you said it is a BC12D, what style ribs does it have? There are so many things going on here that need to be sorted out to get you on the right path. If you want you can give me a call, and I will try to help you get it sorted out. Tom 618-393-2967

[N96337]

Re: is cotton rib stitching legal

In Polyfiber's manual, it calls out for Ployester cord... so that should answer that question...cotton wouldn't be ok, unless they have someone that signed off a major alteration form to deviate from the STC. As far as whether it's legal to lace the wing instead of the wires, I don't want to go down that road again...it's been beaten to death here.
I'm with Rollerton, I'd just factor in a recover job on the wings, unless there's some form of paperwork that approves the alteration from the STC, and go from there. If there is paperwork, then I'd factor it in for "soon" as it's going to deteriorate faster than the polyester fabric...
Mixing and matching systems is not smart, besides not legal.
JH

[Guest]

Re: is cotton rib stitching legal

Well let me take a stab at it.

The installation of the fabric has to be done in accordance with the process and procedure that it was certified with. I doubt that the process would specify cotton thread for stiching as it would not (in theory) have the same life as the covering. If the stiching let go in flight the fabric woudl balloon off the wings and destroy lift. You need to take care of your lift. If you stick to the letter of the law, its probably not airworthy in that condition.

It was common practice at one time to use cotton tapes on poly fabric as some thought they would "stick" better. As you can guess the cotton tapes aged differently than the poly, and usually had to be replaced earlier than desired.

Somehow the idea that you could take a system, for instance Stitts, and mix and match it with parts from another and end up with your own secret recipie for covering and painting an airplane became wide spread. Using different types of glue was another bad idea. Today its not considered a good practice to mix and match.

If it was me looking at that airplane, I would budget to recover the wings and get some adjustment to the price. Or walk.

There are much smarter folks than me here on the forum that can add a lot to this, and hopefully correct my rash statements!

Hi Bob and all,

Maybe some of you have a recollection of this.

In the late 60's maybe '68 I bought a 1939 BL-65 that had been in storage in pieces since '41 (that makes you think of some fellow heading off to war).

In the stack of papers that came with it I remember seeing a sevice letter from T-craft that described how the wings needed to be rib stitched to prevent that balooning of fabric on the upper wing. Apparently some early t-crafts were made without rebstitching.

I have a pretty good memory so I am betting a good part of what I remember is correct. I have pictures of the plane so I am sure I did buy one in '68.

All the paper work went with it when I sold it but I have not heard mention of similar service letter. Ever hear of such a thing?

Thanks, Dave.

[ROllerton]

Re: is cotton rib stitching legal

hi dave.

If you do a search on rib stiching, you should find some previous discussion on the spring wire system that was used for awhile to attach the fabric to the ribs.

I think the general opinion is that the wire was faster to install, the correct (spacing) wire is not easily vailable anymore, your plane had to be certified to use t, your ribs have to have holes drilled in them for the wire, and you are better off to just rib stich it.

The reading gets interesting and the discussion heated because the wire if easier, and we humans prefer the short cut even when its a tad nire risky!

[3Dreaming]

Re: is cotton rib stitching legal

Hi Bob and all,

Maybe some of you have a recollection of this.

In the late 60's maybe '68 I bought a 1939 BL-65 that had been in storage in pieces since '41 (that makes you think of some fellow heading off to war).

In the stack of papers that came with it I remember seeing a sevice letter from T-craft that described how the wings needed to be rib stitched to prevent that balooning of fabric on the upper wing. Apparently some early t-crafts were made without rebstitching.

I have a pretty good memory so I am betting a good part of what I remember is correct. I have pictures of the plane so I am sure I did buy one in '68.

All the paper work went with it when I sold it but I have not heard mention of similar service letter. Ever hear of such a thing?

Thanks, Dave.

The service letter you mention was for the ailerons.

[Guest]

Re: is cotton rib stitching legal

The service letter you mention was for the ailerons.

Thanks Tom!

That makes sense.

It's been a long time and I was sure I saw something like that but being for ailerons makes sense.

Thanks again, Dave.

[Winston L.]

Re: is cotton rib stitching legal

It depends on what method the airplane was covered with and when it was covered. At one time when you covered with ceconite materials the fabric was synthetic but the tapes and rib stitch chord were organic. The standard rib stitch chord even fairly recently has been bee's waxed linen chord. I rejuvinated some DC3 control surfaces recently that were covered by the airforce in the early seventies with razorback fabric but the tapes were cotton and the chord was linen. The important thing is to inspect the condition of the chord. In the case of the DC3 surfaces the chord was deteriorated. I hope this helps. Winston

[ROllerton]

Re: is cotton rib stitching legal

I had heard people would use cotton tapes on dacron based fabric because they believed it would stick better; the dope would bond to it better than it would to a dacron tape. was there another reason, for instance the dacron tapes were not available?


News to me on the lacing thread. Never heard of that before.

[Winston L.]

Re: is cotton rib stitching legal

Synthetic tapes etc. may not have been available, but I am not sure. Since I am not that familiar with the stits process I don't know what there cord is made of. The cord I have used alot; which is approved for ceconite is a linen I am sure. There is also MIL-C2520A cord which I think is the same as ceconite cord. Winston

[wayne turner]

Re: is cotton rib stitching legal

the plane we are talking about was covered in 1972 with ceconite acording to stc sa1351-we, could this be legal? thanks,wayne

[N96337]

Re: is cotton rib stitching legal

I would say Yes, it is... but a quick call to John Goldenbaum @ Polyfiber would get you a definate answer. He'd know for sure.
JH

[Ragwing nut]

Re: is cotton rib stitching legal

I had heard people would use cotton tapes on dacron based fabric because they believed it would stick better; the dope would bond to it better than it would to a dacron tape. was there another reason, for instance the dacron tapes were not available?


News to me on the lacing thread. Never heard of that before.

Bellanca Viking factory use to use cotton tapes on Ceconite. I don't know the reasoning behind it, but it wasn't smart. I have never heard of cotton thread. it has always been waxed linen as far as I can remember.

Mike

[wayne turner]

Re: is cotton rib stitching legal

after 34 years how do you tell the difference between cotton thread and linen thread?I bet it looks the same,and when you burn a string will it burn the same? thanks wayne