Wing Drag Wires

[1938BF50]

Can someone tell me what the original pre-war wing drag wires were coated/plated with? Mine have some silver looking paint/? flaking off. Hard to tell what it may have been. Looked into cad plating....$ouch$. Can I clean them, assemble the wing and epoxy prime after tensioning?

Thanx

[Winston L.]

Re: Wing Drag Wires

They were silver cad plated originally. I primed my wires after cleaning them and they seem to be doing okay. You just have to keep from scratching or nicking them when cleaning.


Winston

[mulwyk]

Re: Wing Drag Wires

I cleaned up mine by stroking them with a scotch-brite pad. Then painted them with white epoxy primer.

Bob Gustafson

[Hank Jarrett]

Re: Wing Drag Wires

You should be OK replacing the CAD with primer and paint from a structural view although I don't know if changing the process is actually "legal". If you are going to remove the flaking CAD remember the stuff is TOXIC heavy metal. You don't want your dog, kids or you eating or breathing the dust or pieces. You also DON'T want any scratches in the wire! DON'T use sand paper to remove the CAD coating (dust and scratches). You are probably OK with scotch brite but be careful with the dust on the pads. That's why it is so expensive getting CAD done now. The disposal cost is rediculous and OSHA looks over teh platers shoulders all the time. If you can get IVD Aluminum it is a wonderful substitute for CAD and very safe to be around (again, don't know how the feds will feel about it).
Hank

[Guest]

Re: Wing Drag Wires

When I last cleaned and painted a set of wires I could not help but to notice the depth and sharpeness of the many notches in the end of the wires that we call theads. A plier scratch compared to those is quite shallow and dull.

Its a good not mare these surfaces and I make every effort not too but wonder if it is as critical as anticipated in these low stress applications compared to high performance aircraft.

As an engineer I beleive I understand the princeples in play. Seems like the designer not would have used those threaded ends if it was very critical or highly stressed.

I understand also that scratches in the middle of an undamped wire will have bigger effect. Of course we dampen these wires with tape at the middle and tend to make scratches at the ends.

I have retired wires to storage for less than a perfect surface. Starting to doubt that was necssary. Fortunately I still have them.

Food for thought, no critiques intended. I guess I am just thinking out loud. That's always dangerous, ask Homer!

Dave

[Hank Jarrett]

Re: Wing Drag Wires

I am a little conservative with the regular Tribe members. If you have a 10 power glass and know what a 10:1 blend looks like you can get away with a lot, BUT I wouldn't want someone who hadn't had some experiance looking at failure surfaces to try to make that kind of judgement (short version, I think we agree). On the CAD part, even though I spent years working around heavy metals, they still scare me. After I left the NADEP working with chrome and CAD plate, we had a man a month die of Cancer! A LOT of those guys were the ones who never took heavy metal dust seriously. Can't make a scientific conection, but those monthly socials with another guy gone each time have had a STRONG effect on my treatment of heavy metal dust teh rest of my life.
Hank
By the way, I had scratches on my tail wires and I replaced them. Never have understood why Taylorcraft uses cut threads instead of rolled. Really surprised me when I looked close and saw it.

[Ragwing nut]

Re: Wing Drag Wires

I have never known of a wire failure in a wing, not that they don't exist. I am more concerned with pitting and try not use any that have it. Tail wires are a little different story though. Cad or even zic plating has become rediculous in costs. My uncle works at Tinker AFB and he said they have gone to electroless nickel due to the disposal costs of CAD.

Mike

[1938BF50]

Re: Wing Drag Wires

Nickel plating is ten cents on the dollar compared to CAD. Any issues if I have the wires and nipples electroless nickel plated?

[Hank Jarrett]

Re: Wing Drag Wires

Do NOT use electro plating of ANY kind unless a proper Hydrogen embritilement relief is done. This generally involves a bake at 375º+-25 F for 23.5 hours (the 30 minutes is just to pull one rack out and put the new one in) and you need to go into the oven within ~30 minutes of coming out of the tank. A really good process is IVD Aluminum (Vacuum Deposited) that doesn't even need a bake. Again, I don't think the FAA will let you change the process without the engineering analysis, and that ain't cheap.
Be VERY careful of the local bumper plat shop. They generally don't do the bake to [roper tollerences and THAT CAN KILL YOU. Our parts may not be high tech, but they are orders of magnitude more critical than a Chevy bumper.
Hank
I also put pits in the same category as scratches. If the wire is pitted, DON'T use it. It isn't worth it.

[Hank Jarrett]

Re: Wing Drag Wires

Whatever they call it, if it goes in a tank of liquid (or they use little wet pads to apply the plate with electricity) it's a form of electroplating. The Hydrogen is in the liquid and the electricity pushes the Hydrogen atoms into the metal.
Hank

[Ragwing nut]

Re: Wing Drag Wires

Nickel and CAD need to be baked and there is a FAA certified plater in Tulsa, OK. I don't see nickel plating any different than CAD plating the wires as legality goes as both are properly applied. Both are corrosion preventatives and if the nickel is applied correctly, structural integrity would be equal to CAD.

Mike

[Hank Jarrett]

Re: Wing Drag Wires

I agree that there isn't anything wrong with Nickel plate from a technical point of view. The problem is it ISN'T what is on the drawing and the FAA is going to jump you for making a process change without going through all the hoops if you get caught. Doing the change "right" (doing a legal process change) will cost more than just going out and getting what is on the drawing. That's why we still fly with Mags when computer electronic ignition would be safer, more reliable and less expensive to buy (not to mention the operational advantages of being able to change the advance on the fly making starting safer and easier and improving economy).
You can go out and change a lot of things on an old plane and most inspectors won’t ever know the difference, but if one who knows what is SUPPOSED to be on your plane ever catches you the fixes could be extensive and expensive! If you screw up and make a change that causes a failure, you could end up dead.
Hank

[Ragwing nut]

Re: Wing Drag Wires

It is a corrosion preventative and should be a minor alteration and log book entry only. No different legally that painting the wires to protect them. Ask Eric for clarification, he is of the FAA type. If you want to get down right technical, I bet 99% of the aircraft out there are not 100% legal in some way. Wrong screws, wrong paint, wrong ply tires, older repairs missing from logbooks, missing or improperly filled out logboks, blah, blah, blah.

Mike

[Forrest Barber]

Re: Wing Drag Wires

The tail wires are tested to 2900# pull with the full system in place, cut thread, nipples and inserts in place. NOW that is plenty. I have never seen a broken drag or anti drag wire upon tear down. The foot of the compression strut deforms first. BAD crash is different , sure they can break on an overload.
Cut thread WERE used at that time. WHY not they certainly passed the test of time, IN todays world it is easier, better, faster to use rolled thread. Yes I have just returned from Univair in Colorado and learned a lot which I will share this week with a report to our PMA Group first , then the general discussion.

[Ragwing nut]

Re: Wing Drag Wires

How is ole Steve Dyer doing. Been a few years since I talked with him. His dad Fred and my grandfather go waaaay back.

Mike