PDA

View Full Version : Nicopress sleave question



Iflylower
10-24-2009, 10:08 PM
I've been told that Copper nicopresses go with Galvanized flying wire and Zinc (silver colored) goes with Stainless wire.

A couple days ago, a local mechanic told me it doesn't matter to mix the two. I'd rather go with Copper, since there is more contrast for inspection on my stainless wire.

Thoughts or concerns?

jgerard
10-24-2009, 11:41 PM
Some where in an old mechanics book I seem to remember that zinc is OK on both types of cable but copper is only supposed to be used on galvanized.

Jason

Alaska_Rallyer
10-25-2009, 12:20 AM
They are all copper nicopress fittings, or "oval sleeves." Some are zinc or tin plated and do not look like a penny but are still copper.
Table 7-6 in AC 43.13-1B has a note that requires the use of plated sleeves on stainless cable.

I dont think its a big deal.

cruiser
10-25-2009, 06:00 AM
Tinned sleeves go with stainless cable. I think it is a corrosion concern. Jim

behindpropellers
10-25-2009, 08:39 AM
Tinned sleeves go with stainless cable. I think it is a corrosion concern. Jim

Probably something with dissimilar metals.

Jim Miller
10-25-2009, 11:28 AM
I had this same question a couple years ago during a rebuild of my Colt. I called nicopress company and spoke with one of their engineers. I was very suprised by what he told me and hopeing some AI type would follow-up on this subject with Nicopress. He told me that neither the copper or zinc plated was supposed to be used on stainless cable as the coating was not as important as the underlying metal (copper). The problem according to him was cracks in the sleeve when pressed onto stainless cable. Another older A&P remembered some some stainless replacement cables made by Piper were recalled in mass due to cracks found in the sleeves on both those in service and new still on the shelf. Before I make any cables for my Cub project I plan to call nicopress again and ask the same question of another engineer.

skywagon8a
10-25-2009, 03:12 PM
I had never heard this mentioned before. Just last week, in preparation for painting, I took off a 3/16" stainless walk cross-wire on a set of EDO 2000s. It had copper nicopress sleeves. I could find no evidence of any corrosion or any other problems. The cable had been on the floats for 39 years and has never been in salt water. I am going to reinstall the same cable with copper.

Darrel Starr
10-25-2009, 08:26 PM
An Internet search turned up this August 2001 Fairbanks FSDO Newsletter and the relevant statement:

Nicopress Sleeves
Recently, a question came up about plated and plain sleeves, and their intended use. John Gamble pointed out the reference in AC 43.13-1B, page 7-34, Table 7-6. The note at the bottom of the table tells us that the plated sleeves are required on stainless steel cables due to electrolysis caused by different types of metals. Thanks John!

http://www.faa.gov/about/office_org/field_offices/fsdo/fai/local_more/maintenance_newsletters/media/Aug01.pdf

http://www.supercub.org/photopost/data//500/medium/Nicopress_Sleeves.jpg

Darrel Starr
10-25-2009, 10:18 PM
To my knowledge, the footnote in the AC 43.13-1b table is the ONLY reference in any official document on this subject. If this were a serious concern by the FAA, there would be much more verbiage on this subject then just an obscure footnote in a table buried in the middle of a large publication. So I would think it is advisory and not a major concern.
Darrel

NimpoCub
10-25-2009, 10:29 PM
My understanding of electrolysis is that two dissimilar metals IN CONTACT W/EACH OTHER can/will cause prob's.

Do you suppose that with the gross malformation of the sleeve as it's pressed into the cable strands that the plating remains "intact" and prevents contact of the copper w/the SS?
I don't.
Flame suit on.

Jim Miller
10-26-2009, 07:26 AM
From field experience it may be a problem in theory only but it is interesting that nicopress told me what they did. The implication is that maybe the FAA has been putting out incorrect info for many years. If any of you A&P's and IA's have the time call nicopress and talk with their engineering department. I am sure all of us would be interested in what they have to say.

bowhunter
10-26-2009, 09:20 AM
What we usually worry about as far as dissimilar metals goes isn't really electrolysis. Galvanic corrosion is the culprit. You will see very small amounts of it (white or discoloration on the surface) just about anywhere you have joined dissimilar metals. Usually not a problem unless the joint is submerged in a liquid (the more acidic the more corrosion). When you do have this situation one of the metals will act as a sacrificial anode. Like the one in your electric water heater or on the lower unit of your outboard motor.

mike mcs repair
10-26-2009, 10:52 AM
hijack....

you want to be impressed, take some old galvanized 1/8" cable say ~10', wrap into a loop say 7" dab some aircraft paint stripper on it in one spot, let dry then throw it in a zip lock bag and hang it on the wall, bag does not need to be sealed..... in a years time the cable will be starting to fray and be eating it self in two....

always hate seeing how poorly people strip metal planes and get stripper on cables a wing root and inspection holes....

Mikey says
try it, you won't like it :-)

tamarack
10-26-2009, 01:05 PM
Good inspection tip about the paint stripper and cables!

And back to the zinc-plated nicopress sleeves, a local IA did lose his license for two deficiencies (that I know of...) one of which was the installation of copper sleeves on stainless cable. While there were more serious issues in the case, this was one item that the FAA could easily prove was done by the IA in question.

Vickie

cruiser
10-27-2009, 06:21 AM
From the weebeastie site http://www.weebeastie.com/hatzcb1/nicopress.html

Jim Miller
10-27-2009, 07:54 AM
The nicopress engineer told me to use only the stainless steel sleeves with stainless steel cable. If the tin plated are OK also that is good news. It would be easy to mix-up tin and zinc plated. Are the 28 series Tin plated? Does this mean that stainless steel cables with plain copper sleeves will have to be replaced and how do you verify if your plated sleeves are tin or zinc.

mike mcs repair
10-27-2009, 08:11 AM
and how do you verify if your plated sleeves are tin or zinc.

scrape a little tin of outside of sleeve.... it should be copper inside???


ok I think this thread is getting carried away dreaming up things to worry about :-) its not rocket science......

StewartB
10-27-2009, 08:30 AM
Anyone seen a nicopress failure? The only one I've ever seen was on a walk wire across a pair of floats. It was the cable that failed, but near the nicopress fitting. Corrosion may have been a factor but more likely it was 20 years of that cable rattling around getting worn. I do keep a close eye on ski rigging. Many of those nicopress fittings have been wrapped in tape to cover sharp cable ends. Probably a bad idea.

SB

Jim Miller
10-27-2009, 09:32 AM
Is it possible that the FAA has made a mistake? The nicopress website clearly shows as others have previously stated on this post that two types of sleeves are intended for stainless cable- Stainless steel sleeves and tin plated copper. If I was reading correctly the 28 series sleeves are zinc plated copper. The tin plated copper are a 428 series and the stainless steel sleeves are 168 series. As the nicopress engineer told me a couple years ago it is not corrosion but the fact that the tin and zinc plated copper use a different copper alloy and that if the wrong one is used it is prone to crack when pressed onto the cable.

StewartB
10-27-2009, 09:42 AM
If its prone to crack...why do they use that alloy? What would that have to do with the cable material?

SB

sekps
10-27-2009, 10:15 AM
http://www.corrosion-doctors.org/Definitions/galvanic-series.htm

Iflylower
10-27-2009, 11:00 AM
I was fat, dumb, and happy with my answers a couple days ago on this thread.

Y'all have muddied the waters a bit...so I'm looking into it. I definitely don't like that a mechanic is loosing an IA over using the wrong sleeve. Probably more to that story, but the point is taken.

I followed the links in the thread. They contradict each other too.
I find it interesting that Aircraft Spruce will sell Galvanized and Stainless flying wire/rope. And, they only sell the plain copper, and zinc plated copper sleeves.

Nicopress themselves, from their website, list it this way....

Nicopress® Oval Sleeves For Steel Aircraft Cable & Wire Rope

Copper & Zinc Plated Copper Oval Sleeves
Aluminum Oval Sleeves

Nicopress® Oval Sleeves For Stainless Steel Aircraft Cable & Wire Rope

Tin Plated Copper Oval Sleeves
Stainless Steel Oval Sleeves

Looks to me like copper and zinc plated are for galvinized wire. Tin plated and Stainless sleeves are for stainless wire. That's pretty sad on AC spruces' side. Wicks lists... Copper-use with Galvanized. Nickel-use with stainless. Zinc - use with stainless. Tinned - use with stainless.

I'm ordering some tinned sleeves now. I'll keep my zinc sleeves off the stainless. Probably much ado over nothing, but I'd like to do it right, no matter.

How about those squeezers for $250. I'll be using my buddies big one for my 90 squeezes. 3 squeezes per sleeve...

Jim Miller
10-27-2009, 12:18 PM
If its prone to crack...why do they use that alloy? What would that have to do with the cable material?

SB

Steward
That is a good question? I don't know why an engineer at nicopress would say that unless it was true. Maybe the stainless cable will allow overcompression of the sleeve where the steel cable won't. I really don't know. I am making some cables very soon and plan to call nicopress again. Being experimental I am considering using stainless steel sleeves.

Steve Pierce
10-27-2009, 06:17 PM
Cal, I have the squeezer and the go/no go gauge you can use. Why use stainless? It frays quicker where the elevator cable goes 180 degrees. My old Wicks catalog always said to use nickel, tinned or zinc plated copper nicropress sleeves on stainless and copper on galvanized. Seems like I checked into it way back and found out they were right.

wirsig
10-27-2009, 06:30 PM
Go to Lowes, they have the squeezers by the cable for $20.
I think I paid $15 because the pair I got were scratched. They work great! Use the go / no go to test'em. I did a series of tests on 1/8th to failure just so see how everything worked. As long as the cable is looped over a thimble and back through the sleeve the cable will break before the sleeve every time.

Iflylower
10-28-2009, 10:03 AM
I bought the stainless cause that's advised for seaplanes.

I don't know when it'll float, but I hope it does some day. I might put all galvanized if I did it again, I liked float flying when I lived in MN, but it just isn't too practical in TN.

I should've looked into it deeper. Any other qualities against stainless wire other than price?

behindpropellers
10-28-2009, 10:13 AM
I bought the stainless cause that's advised for seaplanes.

I don't know when it'll float, but I hope it does some day. I might put all galvanized if I did it again, I liked float flying when I lived in MN, but it just isn't too practical in TN.

I should've looked into it deeper. Any other qualities against stainless wire other than price?

Cal-

I would only use the stainless for your rudder cables.

Tim

mike mcs repair
10-28-2009, 10:29 AM
Any other qualities against stainless wire other than price?

yup don't last as long as galvanized.... unless you are around salt water and corrosion is an issue..... galvanize is all I use, unless specifically requested

twoton
10-29-2009, 02:59 PM
I did talk with a Nicopress engineer whom stated that only tin plated copper sleeves are recommend for Stainless Cables and also SS sleeves. The tin plated are made from a different alloy of copper and will not form stress related cracks due to corrosion. The tin is only used to help identify the sleeve. The regular copper and zinc plated ones can result in corrosion of the copper in contact with SS that comes from being under stress.

Jim Miller
10-29-2009, 04:12 PM
Twoton
That's what I was told also. Looks like the chart in AC43 should be updated as it gives the impression that the 28 series sleeves should be used with stainless steel and does not mention the 428 series which are the tin plated ones.

Thanks
Jim Miller

Fabman
10-30-2009, 09:51 AM
stress related cracks due to corrosion

Cracks where?

I just helped my friend replace all of his SS control cables on his Cub. He has put about 3700 hrs on it since 1993 when we rebuilt it. He has had it on floats every year. At the time we didn't know about the tin plated sleeves. He replaced the cables because of some flat spots on the rudder cables (no broken strands though). We replaced with SS and tin plated sleeves.