Martin wire

[LostnSpace]

Re: Martin wire

I see where David Rude has some taylorcraft wire for sale on the Stuff for sale side

[SpecialT]

Re: Martin wire

That was a special case where we wanted to do several of the same make and model planes at the same time with a group of owners doing the assists. The IAs time was used in a day. The total man hours were more than just his time. There can be huge efficiencies when you batch load work.

Hank

Man you guys on the east coast have all the fun. I need a condition inspection and wish you were around...

[Hank Jarrett]

Re: Martin wire

Wish we still had half a dozen "T"s at the local fields here. It was great when we had a bunch of the same planes close.

[N96337]

Re: Martin wire

If you're not covering your edges on stamped ribs with anti chafe tape, you're in total violation of the covering STC's anyway. Hank, normally I'm totally impressed with your logic, but you're so far off base on this, it's pathetic. You go right ahead and modify wires to hold on the fabric....it's a far inferior system to rib stitching. I've only been an IA for 35 years, and I've seen a handfull of rib stitches broken in that time (I do primarily fabric aircraft) and those were on a truss rib. If it's so dangerous, then damned near every Super Cub in the country is going to fall out of the sky, with those stamped Univair replacement ribs. As was said previously, the ONLY reason for the wire was labor costs. If your fabric is flopping around that much that it is going to chafe that cord, you've got more problems. I think I can say I've seen a few fabric aircraft and I've yet to see a problem. Did this one rib stitch that you saw broken lead to a problem?

[astjp2]

Re: Martin wire

Actually Hank, I did get it approved by field approval, and the stamped ribs for the cub type aircraft are pretty much the same type of form as Taylorcraft ribs. This is a MAJOR alteration and thusly I was able to get it field approved based on similar applications and installations after some haggling with FSDO. I perfer rib lacing over any rivets or screws because you dont damage the ribs when recovering. Tim

oh and that was an a piece of a 337 that I posted several years ago.

Problem with stitching is it is NOT approved for stamped rib wings. Even though I tend to roll my eyes at many things the Feds say is "not approved" this one is a good one. The stamped ribs do NOT have the edge of the rib rolled under far enough to clear the stitching cord. The cords will rub on the sharp edge and can be cut by the edge of the ribs. If you are going to rib stitch a stamped rib you need to either roll the edge in far enough ON EVERY RIB that the cord does NOT touch the sharp edge or you need to put something over the edge to protect the cord. Doing this "SHOULD" require some kind of official approval since it modifies the rib and or the covering procedure specified in the Type Certificate. If it isn't shown in the log book you are probably NOT LEGAL and probably NOT SAFE!!!!! That was the safety of flight part of the rant.

The LEGAL part of the rant is that Taylorcraft NEVER approved of rib stitching on stamped ribs. The letter floating around from Dorthy Ferris is for a PRE WAR ribbed wing with stick ribs. Those planes WERE rib stitched. You can use stitches on ANY stick rib wing, even if it is on a post war plane. You CAN NOT use stitching on a POST WAR WING even if it is on a PRE WAR plane! If you stitch a stamped rib wing you are putting your life and your mechanics certificate at risk. If you HAVE a stitched wing wing stamped rib you really should open up the inspection covers and take a CAREFUL look inside for dangling stitching cords. They DO get cut! Remember that Taylorcraft DID allow the substitution of one type rib for another on ANY WING so many aircraft have a mix of ribs. You CAN NOT use wires on stick ribs and you SHOULD NOT use stitching on a stamped rib. There are lots of planes with a mix of ribs, and YES, that means there SHOULD BE wings with some ribs stitched and some with wires.

Hank

I am NOT addressing all of the wings that have STCs or other approvals for screws or rivets. That is a whole different "Kettle of Fish".

[astjp2]

Re: Martin wire

People please be nice, we do not want any insults on the forum. If you have an argument, keep it civil and logical. Tim

[waltermrich]

Re: Martin wire

When I used rivets there was no drilling the hole was already there, it did not damage the rib , thats probably why its approved , removal also will not damage the rib , The one draw back is that they are visible under the fabric but not more than screws I would think but more than wire . Whis I could get the wire but its made from unobtainium, maybe some day an affordable material will come about, it did not take long to install an entire wing, stitching is for the birds

[astjp2]

Re: Martin wire

The damage occurs upon removal of the rivets.

When I used rivets there was no drilling the hole was already there, it did not damage the rib , thats probably why its approved , removal also will not damage the rib , The one draw back is that they are visible under the fabric but not more than screws I would think but more than wire . Whis I could get the wire but its made from unobtainium, maybe some day an affordable material will come about, it did not take long to install an entire wing, stitching is for the birds

[astjp2]

Re: Martin wire

The damage occurs upon removal of the rivets.

When I used rivets there was no drilling the hole was already there, it did not damage the rib , thats probably why its approved , removal also will not damage the rib , The one draw back is that they are visible under the fabric but not more than screws I would think but more than wire . Whis I could get the wire but its made from unobtainium, maybe some day an affordable material will come about, it did not take long to install an entire wing, stitching is for the birds

[mike lutz]

Re: Martin wire

Over the years I have drilled out hundreds and hundreds of rivets with no damage to the rib. These were on Gruman Ag-Cat and American Champion, and a couple Aeronca,s. They can be drilled with a #30 drill bit and come right out as they are somewhat soft. Maybe I was lucky, as I have yet to have a problem. My personal preference is to use the rivets in place of the screws. I rib stitch the truss ribs on others. I know there will be some who disagree with me but that's ok. These aircraft are still flying years later with no problems. Just my two cents worth. On a side note, I did a Tri-pacer recover years ago that had martin wire in place of stitching on the truss ribs, and after seeing how thin the rib material is and the worn holes it scared the crap out of me. I don't know if this is legal or not on the truss ribs but common sense tells me it is not a good idea on this type of rib.

[Hank Jarrett]

Re: Martin wire

If you're not covering your edges on stamped ribs with anti chafe tape, you're in total violation of the covering STC's anyway. Hank, normally I'm totally impressed with your logic, but you're so far off base on this, it's pathetic. You go right ahead and modify wires to hold on the fabric....it's a far inferior system to rib stitching. I've only been an IA for 35 years, and I've seen a handfull of rib stitches broken in that time (I do primarily fabric aircraft) and those were on a truss rib. If it's so dangerous, then damned near every Super Cub in the country is going to fall out of the sky, with those stamped Univair replacement ribs. As was said previously, the ONLY reason for the wire was labor costs. If your fabric is flopping around that much that it is going to chafe that cord, you've got more problems. I think I can say I've seen a few fabric aircraft and I've yet to see a problem. Did this one rib stitch that you saw broken lead to a problem?

John,
Like I said, I'm not going to argue on this, but a couple of corrections to your statements. From a SAFETY stand point covering the sharp edge would work fine, I never said it wouldn't. Rolling the edge under so it doesn't contact the rib edge would work fine too. That is from a SAFETY standpoint. If it was a home built I would have no problem doing either one. From a LEGAL standpoint no one has yet posted a document from the FAA APPROVING doing this. I have been sent copies of letters REQUESTING a deviation. I have been sent FAA documents (STCs) for rivets and screws, but nothing that confirm the FAA APPROVES stitching a Taylorcraft stamped rib. I have a letter from Dorthy saying you can substitute stamped ribs for stick and stick for stamped but is says NOTHING about using one fastening method on the other.

I am really happy for you that you have only seen a hand full of cut stitches (which to me confirms my position any way) but the wing I stripped the covering from was FULL of them. I will stand by my decision, if only for me. I won't fly a stamped rib plane with rib stitches. You make your decision based on your risk tolerance, I have made mine. If you had stick ribs with cut cords I would be digging further to find out why. Rodents chewing? No tape over the rib edge? Bad cords? I'm all ears. I fly a 41 with stick ribs and rib stitches. I am restoring a 45 with stamped ribs. All info is good for me and I respect your knowledge....sometimes I am just more risk averse than even my own IA.

As for the wires, I DO NOT like modifying the Martin wires for a Taylorcraft. I have yet to see it done in a way I would use. They just don't fit and I can't figure out a way to make them fit (plus, again, there is NO APPROVAL for using them on a Taylorcraft) Taylorcraft wires DO NOT require modification and work fine. I agree they probably did it to save money, but I have yet to see one (DONE PROPERLY) that had any problems. No matter what method was used if the fabric was "flopping around" the plane should be grounded immediately. Only an idiot would fly with a known condition like that.

I LIKE rib stitching (I use it for the other surfaces and it is fun to do (yea, I know I'm a little nuts, but everybody here knows that already). I also like the Taylorcraft wires. Easier to do and no knots to mess up. As a plus, it is the method used by the factory and no one YET has provided a document showing stitching is approved for Taylorcraft stamped ribs. A letter requesting deviation doesn't cut it. Where is the APPROVAL. As to your last question, no, the wing I was taking the covering off of had NOT been a failure, but there were a LOT of cut cords and they were all cut right at the edge of the rib. Is that a problem? Yea, I kind of think so. I don't need to see wreckage or blood to think there is a problem. There were more un-cut than cut, but how many is too many? For me (and I am not saying this is law for everyone else) I don't want ANY cut cords! NONE! If I see one, how many am I unable to see? I would probably put a new stitch in the failed area, but I would also get my A&P and IA involved. I have grounded my plane for a lot less. But then, I want to die in bed, not tearing up my plane.

Hank

[3Dreaming]

Re: Martin wire

The way I see it is that there isn't a prohibition on lacing stamped ribs. However if you are going to use other than the Taylorcraft wire for an airplane that originally used Taylorcraft wire, you need a field approval from the FAA. AC 43.13.1B clearly states that this is a major alteration. The Poly Fiber manual concurs that a field approval is needed. There is ample evidence that the FAA will grant field approvals for stitching in place of the wire, while not a blanket approval it is an FAA approval for that particular aircraft.

[Hank Jarrett]

Re: Martin wire

Sounds like Tom had drilled down to the heart of the difference of opinion. If it is a "major alteration" to stitch in place of the wire, you need a field approval.....which the FAA seems willing to provide. What would be valuable to the Tribe at large would be the wording to use in the log, and any covering and stitching instructions needed to do a safe and secure job beyond what is in the 43.13.1B.
I would suggest the instructions should include a warning to insure the cords will NOT rub on the edge of the ribs by either modifying the edge or covering it to prevent abrasion. If that was in the logs I would feel the assumed risk was reasonable.
Anyone want to take a shot at a sample log entry? We also need to have the information showing how to do it, how to ask for approval and a sample of an approved plane from the FAA. That will grease the skids for the next guy and provide comfort to any "new guy" at the FAA who will like seeing that someone else has approved it before. I would suggest we also state that Martin wire is NOT a good idea on a Taylorcraft!

Hank

This kind of discussion is one of the things that makes this group so valuable. We look for solutions, not arguments.

[Scott]

Re: Martin wire

Risk Is an interesting thing, it is perceived to exist when it really doesn't.

The perception of risk in aviation causes much unnecessary angst and wasted resources. Perhaps the worst example of this is the requirement for fire/rescue response at airports. There is no objective risk analysis that can make a legitimate case for it, but we (the industry) spends Billions on it every year. If you directed those dollars to, for example runway excursions and controlled flight into terrain, lives would actually be saved, but there is a "public expectation" for fire services at airports so we continue the facade.

All this to say that in aviation in particular, we owe it to ourselves to ensure we're managing real as opposed to perceived risk. Look at the data, the history, the mistakes of others, the engineering realities, and direct your hard earned resources to where they will actually have a positive impact. (which by the way is not always the regulated options).

[astjp2]

Re: Martin wire

Its already covered in the process...that you need to have tape over the rib lacing, if done properly, its not an issue.

Sounds like Tom had drilled down to the heart of the difference of opinion. If it is a "major alteration" to stitch in place of the wire, you need a field approval.....which the FAA seems willing to provide. What would be valuable to the Tribe at large would be the wording to use in the log, and any covering and stitching instructions needed to do a safe and secure job beyond what is in the 43.13.1B.
I would suggest the instructions should include a warning to insure the cords will NOT rub on the edge of the ribs by either modifying the edge or covering it to prevent abrasion. If that was in the logs I would feel the assumed risk was reasonable.
Anyone want to take a shot at a sample log entry? We also need to have the information showing how to do it, how to ask for approval and a sample of an approved plane from the FAA. That will grease the skids for the next guy and provide comfort to any "new guy" at the FAA who will like seeing that someone else has approved it before. I would suggest we also state that Martin wire is NOT a good idea on a Taylorcraft!

Hank

This kind of discussion is one of the things that makes this group so valuable. We look for solutions, not arguments.