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Cable rust

PostPosted: Sun Jun 07, 2015 12:15 am
by barry767
After one year of flying my Higlander I just noticed what appears to be areas of rust along all for 4 wire cables that connect the horizontal stab to the vertical stab. Most of it came off with a little Scotchbrite treatment. Has anyone else seen this and if so, any ideas for preventative treatment? I guess I can always replace them with stainless steel cables, but would only want to do this as a last resort.
Barry

Re: Cable rust

PostPosted: Sun Jun 07, 2015 5:28 am
by messenger
I have the same problem, you can use corrosion X to help prolong the life, but you will have to replace them eventually. I switched to stainless aircraft cable. If you look at the leading edges of the flap and aileron cables at the point where they wrap around the thimble, , you will notice more rust, so cable replacement in those locations is inevitable. I wish stainless cable had been used or recommended in the first place.

Re: Cable rust

PostPosted: Sun Jun 07, 2015 7:18 am
by Johnny C!
I caught on to this issue with the recommended
galvanized cable from another builder, Dennis
C, I think it was, and bought the stainless in
time for original installation in Lima Charlie.
It's not a huge deal to replace any or all of the
cables, but I built her to fly, not to tinker.

If you do convert to stainless, make sure
you get the plated crimping ferrules. The
copper colored ones are not chemically
compatible with the stainless cable.

Good Luck!

John

Re: Cable rust

PostPosted: Sun Jun 07, 2015 7:55 am
by danerazz
The plated ferrules for stainless are correct, but there is a lot of info out there that suggests if you use the "wrong" ferrules the failure time would likely be beyond the service life of the cables. Also, it is visually impossible to tell the plated vs unplated ferrules apart, so you have to know what you ordered.

Re: Cable rust

PostPosted: Sun Jun 07, 2015 2:13 pm
by Johnny C!
The ferrules supplied with my kit were copper
colored, and I would assume were bare copper,
and the plated ones that I ordered from AS to
go with the stainless cable were silver in color,
so I would assume those are clear zinc plate.

John

Re: Cable rust

PostPosted: Mon Jun 08, 2015 12:21 am
by danerazz
SS cables should use tin plated sleeves, regular steel cables should use copper or zinc plated sleeves. The tin and zinc sleeves are visually indistinguishable from each other.

Re: Cable rust

PostPosted: Mon Jun 08, 2015 12:34 am
by danerazz
Also here is a Glasair service bulletin directly related to this subject (cut and pasted):

GLASTAR SERVICE BULLETIN 41
Subject: NicoPress sleeves (P/N 450-0002-004)
Applicability: All GlaStar fuselage kits shipped prior to 11/24/98
Discussion: It has come to our attention that the NicoPress sleeves (P/N 450-0002- 004) we have been supplying for use on the flight control and tailwheel steering cable assemblies may be of an improper variety. According to a strict reading of the military specification for cable swaging sleeves (MS51844), only tin-plated copper or stainless steel sleeves should be used with stainless steel cable. The sleeves we have been providing are either zinc-plated copper or plain copper. The specification of particular sleeve materials for use with particular cable types is dictated by concerns of dissimilar- metals corrosion.
We believe that the chance of premature cable deterioration due to the use of incompatible NicoPress sleeves is so small as to be negligible. We consulted our cable assembly vendor, who concurred with our assessment that the mismatch between sleeve and cable was extremely unlikely to cause any difficulties, given the operating environment of the cable assemblies in question. Further evidence that this is not a serious problem can be deduced from the fact that prominent aircraft supply houses like Aircraft Spruce & Specialty and Wicks Aircraft Supply offer only zinc-plated or plain copper sleeves, and their catalogs either make no specific callout of which sleeve to use with stainless steel cable (Spruce) or make an incorrect callout (Wicks) according to the Military Specification.
Recommended Action: Inspecting cables assemblies for corrosion should naturally be part of every annual condition inspection. The only action we recommend pursuant to this bulletin is to pay particular attention to the NicoPress swages while conducting such inspections. We do not feel that the time or expense of replacing completed cable assemblies is justified by any reasonable safety concern.
From this point forward, Stoddard-Hamilton will stock only tin-plated copper or stainless steel sleeves per MS51844. If you wish to upgrade to these sleeves, please order P/N 450-0002-004.

Re: Cable rust

PostPosted: Mon Jun 08, 2015 11:39 am
by Tralika
It doesn't make me warm and fuzzy knowing that my ferrules are covered with shrink wrap and really can't be inspected.

Re: Cable rust

PostPosted: Mon Jun 08, 2015 12:28 pm
by Johnny C!
I didn't shrink wrap my ferrules. I
only captured the free end of the
cable, inboard of the ferrule. I
wanted preclude water being
trapped at the ferrule.

John

Re: Cable rust

PostPosted: Mon Jun 08, 2015 12:36 pm
by Johnny C!
Image

Re: Cable rust

PostPosted: Mon Jun 08, 2015 7:28 pm
by barry767
Thanks all. I've decided to go ahead and replace all 6 tail cables with stainless and treat the exposed portions of the flap and aileron cables with a corrosion prevententative as well as keeping a close eye on their condition.
Barry