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rudder cable questions

amekler

Well Known Member
Patron
Is there supposed to be snap bushing thru this hole(see photo)
also the rudder cable rubs on the aft grommet-see photo[/ATTACH] how do I fix this?

A.Mekler
RV-12
 

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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.
 
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
 
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.
 
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.
 
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:

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[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:

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[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.
 
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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 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.
 
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?
 
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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