control cable protection question

[Dick[_1_]]

Wanting to use a nylon sleeve over a 1/8" elevator cable to avoid rubbing on
another crossing in mid-fuselage, what do you think about the following
methods of securing the sleeve/tube so it doesn't slip out of position:

slip sleeve over RTV'd cable section; clamp sleeve ends with safety wire;
suggestion...

[Peter Dohm]

"Dick" > wrote in message
news:cfGBj.17591$er2.16977@trnddc08...
> Wanting to use a nylon sleeve over a 1/8" elevator cable to avoid rubbing
> on another crossing in mid-fuselage, what do you think about the following
> methods of securing the sleeve/tube so it doesn't slip out of position:
>
> slip sleeve over RTV'd cable section; clamp sleeve ends with safety wire;
> suggestion...
>
Beyond the obvious, that this should have been addressed in the plans, my
first suggestion is to ask one of your chapter's technical advisors.

There is much more to the EAA than Sport Aviation, although this issue may
well have been addressed in a back issue of one of their magazines, and the
chapter system may well be the true backbone of the organization and the
entire movement. They also operate a bookstore, and it is very likely that
this issue was addressed in one of Tony Bingelis' (sp?) books.

Going back to your original question, although I am not a mechanic, I have
normally seem this roblem addressed by the use of "fair leads" attached to
the structure. The issue is certainly addressed in Part 43, so that any
mechanic will have a reference source, and may be in "AC 43.13.2A" which can
be obtaied from:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/E533BB05389C90E486256A54006E47B2?OpenDocument
and you can just past the AC number into Google if the link is too long.

BTW, your proposed method looks like a dangerous source of both binding and
corrosion--at least to me.


Peter

[jerry wass]

Dick wrote:
> Wanting to use a nylon sleeve over a 1/8" elevator cable to avoid rubbing on
> another crossing in mid-fuselage, what do you think about the following
> methods of securing the sleeve/tube so it doesn't slip out of position:
>
> slip sleeve over RTV'd cable section; clamp sleeve ends with safety wire;
> suggestion...
>
>
>
Use heat shrink electrical tube to secure sleeve----Some RTV sealants
are corrosive--especially if they smell like vinegar!

I've seen teflon tubing for sale somewhere---maybe electrical suppliers?

[Dick[_1_]]

thanks, I just forgot about heat shrink tubing and didn't know about vingery
smelling RTV..
"Jerry Wass" > wrote in message
. net...
> Dick wrote:
>> Wanting to use a nylon sleeve over a 1/8" elevator cable to avoid rubbing
>> on another crossing in mid-fuselage, what do you think about the
>> following methods of securing the sleeve/tube so it doesn't slip out of
>> position:
>>
>> slip sleeve over RTV'd cable section; clamp sleeve ends with safety
>> wire; suggestion...
>>
>>
>>
> Use heat shrink electrical tube to secure sleeve----Some RTV sealants are
> corrosive--especially if they smell like vinegar!
>
> I've seen teflon tubing for sale somewhere---maybe electrical suppliers?

[[email protected]]

On Mar 12, 7:33 am, "Peter Dohm" > wrote:

> BTW, your proposed method looks like a dangerous source of both binding and
> corrosion--at least to me.
>
> Peter

And an uninspectable spot. It's unorthodox, at least, and should
be avoided. The cables need to be rerouted via fairleads or rubbing
blocks to separate them, not sleeved.

Dan

[Dick[_1_]]

actually fuselage belly has an inspection/access cover. Thanks though.
> wrote in message
...
> On Mar 12, 7:33 am, "Peter Dohm" > wrote:
>
>> BTW, your proposed method looks like a dangerous source of both binding
>> and
>> corrosion--at least to me.
>>
>> Peter
>
> And an uninspectable spot. It's unorthodox, at least, and should
> be avoided. The cables need to be rerouted via fairleads or rubbing
> blocks to separate them, not sleeved.
>
> Dan
>

[[email protected]]

On Mar 13, 6:37 am, "Dick" > wrote:
> actually fuselage belly has an inspection/access cover. Thanks > wrote in message
>
> ...
>
> > On Mar 12, 7:33 am, "Peter Dohm" > wrote:
>
> >> BTW, your proposed method looks like a dangerous source of both binding
> >> and
> >> corrosion--at least to me.
>
> >> Peter
>
> > And an uninspectable spot. It's unorthodox, at least, and should
> > be avoided. The cables need to be rerouted via fairleads or rubbing
> > blocks to separate them, not sleeved.
>
> > Dan

I meant that the cable itself, with a sleeve over it, would
not be inspectable through that area. Any corrosion or fraying would
go unnoticed.

Dan

[Bob Kuykendall]

On Mar 12, 7:33*am, "Peter Dohm" > wrote:
> ...Going back to your original question, although I am not a mechanic, I have
> normally seem this roblem addressed by the use of "fair leads" attached to
> the structure...

That's the way I'd approach it as well. The sleeve thing sounds sort
of hokey, and I'm sure it'd look sort of hokey, and it has the
inspection issue against it. I take primary flight control systems
fairly seriously, and I consider pitch to be the most important of the
primaries.

My preference would be to attach fairlead thingies like these to the
structure to guide both cables where they threaten to rub:

http://www.aircraftspruce.com/catalog/appages/fairleads.php

I remember replacing them on gliders such as Schweizer 2-33, except
that back in the day they were some sort of dense, oil-impregnated
wood. The nylon will last longer and probably cause less cable wear.

AC43.13 para 7-149-n suggests that the cable angle change at a
fairlead be no greater than 3 degrees, and that's probably a good
guideline for a tensioned cable. Much more than that, and the fairlead
wears through rather quickly. Better to use a pulley then.

Thanks, Bob K.

[Highflyer]

"Dick" > wrote in message
news:Ud9Cj.19481$er2.14960@trnddc08...
> actually fuselage belly has an inspection/access cover. Thanks though.
> > wrote in message
> ...
>> On Mar 12, 7:33 am, "Peter Dohm" > wrote:
>>
>>> BTW, your proposed method looks like a dangerous source of both binding
>>> and
>>> corrosion--at least to me.
>>>
>>> Peter
>>
>> And an uninspectable spot. It's unorthodox, at least, and should
>> be avoided. The cables need to be rerouted via fairleads or rubbing
>> blocks to separate them, not sleeved.
>>
>> Dan
>>
>


An access cover in the belly does NOT make the cables inspectable when they
are covered by a sleeve. Can you detect broken strands?
Separate them positively with a pulley or fairleads please. It doesn't add
much weight and will prevent all kinds of wear and corrosion problems while
remaining inspectable.

Highflyer
EAA Technical Counselor
FAA Technical Safety Counselor

>

[cavelamb himself[_4_]]

Highflyer wrote:
> "Dick" > wrote in message
> news:Ud9Cj.19481$er2.14960@trnddc08...
>
>>actually fuselage belly has an inspection/access cover. Thanks though.
> wrote in message
...
>>
>>>On Mar 12, 7:33 am, "Peter Dohm" > wrote:
>>>
>>>
>>>>BTW, your proposed method looks like a dangerous source of both binding
>>>>and
>>>>corrosion--at least to me.
>>>>
>>>>Peter
>>>
>>> And an uninspectable spot. It's unorthodox, at least, and should
>>>be avoided. The cables need to be rerouted via fairleads or rubbing
>>>blocks to separate them, not sleeved.
>>>
>>> Dan
>>>
>>
>
>
> An access cover in the belly does NOT make the cables inspectable when they
> are covered by a sleeve. Can you detect broken strands?
> Separate them positively with a pulley or fairleads please. It doesn't add
> much weight and will prevent all kinds of wear and corrosion problems while
> remaining inspectable.
>
> Highflyer
> EAA Technical Counselor
> FAA Technical Safety Counselor
>
>
>
>

I know that everyone wants to think that homebuilts are built better
than anything else, but I've seen this kind of thing too often to
accept that wisdom.


To the OP, a teflon or delrin (high density plastic fairlead would be
the proper way to protect a cable from chaffing.

[Dick[_1_]]

good point on hidden cable strands. i will use fairlead or delron..
"Highflyer" > wrote in message
...
>
> "Dick" > wrote in message
> news:Ud9Cj.19481$er2.14960@trnddc08...
>> actually fuselage belly has an inspection/access cover. Thanks though.
>> > wrote in message
>> ...
>>> On Mar 12, 7:33 am, "Peter Dohm" > wrote:
>>>
>>>> BTW, your proposed method looks like a dangerous source of both binding
>>>> and
>>>> corrosion--at least to me.
>>>>
>>>> Peter
>>>
>>> And an uninspectable spot. It's unorthodox, at least, and should
>>> be avoided. The cables need to be rerouted via fairleads or rubbing
>>> blocks to separate them, not sleeved.
>>>
>>> Dan
>>>
>>
>
>
> An access cover in the belly does NOT make the cables inspectable when
> they are covered by a sleeve. Can you detect broken strands?
> Separate them positively with a pulley or fairleads please. It doesn't
> add much weight and will prevent all kinds of wear and corrosion problems
> while remaining inspectable.
>
> Highflyer
> EAA Technical Counselor
> FAA Technical Safety Counselor
>
>>
>
>

[cavelamb himself[_4_]]

Dick wrote:

> good point on hidden cable strands. i will use fairlead or delron..


Good Man!

As a side issue, remember that the cable WILL be excited (mechanically,
if not emotionally), and will want to wiggle all over the place.

(Got to be a better description for this oscillation, but...)

Anyway, cable throught a fairlead (rather that rubbing over a flat
edge) will kill the oscillation at that point - and the cable will
stay in one place.

Fairleads - rather than a protective edge.

Did that make any sense at all???


Richard (I think)