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  #1  
Old 10-25-2021, 08:08 PM
amekler amekler is offline
 
Join Date: Aug 2009
Location: Gilford,NH
Posts: 136
Default rudder cable questions

Is there supposed to be snap bushing thru this hole(see photo)
also the rudder cable rubs on the aft grommet-see photo[ATTACH]Click image for larger version

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ID:	17507[/ATTACH] how do I fix this?

A.Mekler
RV-12
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Last edited by amekler : 10-26-2021 at 06:10 AM. Reason: addition
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  #2  
Old 10-25-2021, 09:07 PM
rmarshall234 rmarshall234 is offline
 
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Location: San Diego, CA
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photo 1 - yes. You should add a grommet. You can cut it on a bandsaw and slip the cable thru if necessary then snap in place.

photo 2 - that's a problem. The cable changes direction as it goes thru that grommet and will eventually cut through and then it's metal on metal. You should have a fairlead there.
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  #3  
Old 10-26-2021, 09:44 AM
amekler amekler is offline
 
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Location: Gilford,NH
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just went back and removed the seat cover
the plastic sheath over the cable was not forward enough
it is supposed to go through that hole and extend 3/8 of an inch so no grommet will be needed there.
Alan
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  #4  
Old 10-26-2021, 09:55 AM
rmarshall234 rmarshall234 is offline
 
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Location: San Diego, CA
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And I looked at that second photo again and what looks like the cable changing directions might just be a reflection. It looks now like the cable is merely resting on the grommet. You're probably fine but I would inspect it after some use. This is a flight control cable afterall.
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  #5  
Old 10-26-2021, 12:01 PM
gasman gasman is online now
 
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Location: Sonoma County
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Quote:
Originally Posted by rmarshall234 View Post
photo 1 - yes. You should add a grommet. You can cut it on a bandsaw and slip the cable thru if necessary then snap in place.

photo 2 - that's a problem. The cable changes direction as it goes thru that grommet and will eventually cut through and then it's metal on metal. You should have a fairlead there.
Easy to cut with a Stanley knife.
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  #6  
Old 10-27-2021, 09:50 AM
mwardle7 mwardle7 is offline
 
Join Date: Oct 2009
Location: Utah
Posts: 96
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For reasons that baffled me when I was building and still makes no sense to me, Van's does not have snap bushings in all of the bulkhead holes that control cables pass through.

In Section 21-14, there are specific instructions to insert bushings in to some holes and not others. The red arrows identify those where bushings are not added:


[Image is cropped. Click here for the full image]

In Section 32-14, you can see the control cables passing through holes that lack bushings:


[Image is cropped. Click here for the full image]

So, make sure you read the instructions and then decide how you want to handle the holes that lack snap bushings.

Last edited by mwardle7 : 10-27-2021 at 09:52 AM.
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  #7  
Old 10-27-2021, 11:53 AM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by mwardle7 View Post
For reasons that baffled me when I was building and still makes no sense to me, Van's does not have snap bushings in all of the bulkhead holes that control cables pass through.
In an attempt to relieve the bafflement...........

Holes that are guiding the cables through a change of direction have snap bushings.
Holes that are aligned with a straight run of the cable, particularly ones that are close by another hole that does have a snap bushing, do not have snap bushings.
The reason being that when the cable is taught from pressure on the pedals it should pass through the center of the hole on a straight run portion, and not make contact.
This has been monitored on the prototypes and after accumulating a lot of hrs, There has not been any evidence of wear on the cable or bulkhead.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

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  #8  
Old 10-27-2021, 01:22 PM
mwardle7 mwardle7 is offline
 
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Thanks for the explanation!
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  #9  
Old 10-27-2021, 08:10 PM
McStevens McStevens is offline
 
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Location: Edmonds, WA
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This design has always baffled me. I'm glad the prototype is fine and it's apparently worked in service, but it doesn't seem like a very good practice.

Do any other aircraft use snap bushings instead of actual fairleads?
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  #10  
Old 10-27-2021, 10:16 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by McStevens View Post
This design has always baffled me. I'm glad the prototype is fine and it's apparently worked in service, but it doesn't seem like a very good practice.

Do any other aircraft use snap bushings instead of actual fairleads?
If by other you mean other than the RV-12?

Yes

All of the RV models use snap bushings as rudder cable fair leads.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
FAA/DAR
RV-6A (aka "Junkyard Special ")
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