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Rotax ignition wiring

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jrevens

Joined: 21 Nov 2013
Posts: 34
Location: Arvada, CO

Posted: Thu Nov 19, 2015 7:12 pm Post subject: Rotax ignition wiring

This may be a dumb question, but would using a shielded twisted pair for the combined ignition control wiring to both modules be OK, or are 2 individual shielded single conductor wires preferred for some reason?  I am basically using Bob's Z-16 diagram... I am very grateful to have that, Bob!

_________________
John Evens
Thorp T-18 N71JE (sold)
Kitfox SS7 N27JE (built & flying)

user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Thu Nov 19, 2015 7:46 pm Post subject: Re: Rotax ignition wiring

It is better to have individual wires for each ignition to prevent one electrical problem from disabling both ignitions.  The shield on each ignition wire (on my Rotax powered RV-12) is separated in the middle.  The shield is grounded at each end.  I suspect that Van's designed it that way to prevent starter current from burning open the shield if the engine ground wire ever breaks.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Nov 20, 2015 5:53 am Post subject: Rotax ignition wiring

At 09:12 PM 11/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "jrevens" <jrevens(at)comcast.net>



 This may be a dumb question, but would using a shielded twisted pair for the combined ignition control wiring to both modules be OK, or are 2 individual shielded single conductor wires preferred for some reason?  I am basically using Bob's Z-16 diagram... I am very grateful to have that, Bob! 	


   My pleasure. What you propose would be fine.

   Do you already have some twisted pair 20 or

   18AWG?



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Nov 20, 2015 5:55 am Post subject: Rotax ignition wiring

At 09:46 PM 11/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 It is better to have individual wires for each ignition to prevent one electrical problem from disabling both ignitions.  The shield on each ignition wire (on my Rotax powered RV-12) is separated in the middle.  The shield is grounded at each end.  I suspect that Van's designed it that way to prevent starter current from burning open the shield if the engine ground wire ever breaks. 	


    Interesting . . . not sure I understand

    why that would be 'better' . . . I like

    to see the designer's white paper on the

    thought process.



 

   Bob . . .

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Fri Nov 20, 2015 5:06 pm Post subject: Rotax ignition wiring

All, The ignition modules and the pickups together cost almost $4,000 to replace. A few feet of shielded wire costs what, $1.49? I'd wire it exactly as Rotax says rather than experiment.



Rick Girard

On Fri, Nov 20, 2015 at 7:53 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 09:46 PM 11/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>



 It is better to have individual wires for each ignition to prevent one electrical problem from disabling both ignitions.  The shield on each ignition wire (on my Rotax powered RV-12) is separated in the middle.  The shield is grounded at each end.  I suspect that Van's designed it that way to prevent starter current from burning open the shield if the engine ground wire ever breaks. 	


    Interesting . . . not sure I understand

    why that would be 'better' . . . I like

    to see the designer's white paper on the

    thought process.



 

   Bob . . .  

	




-- 

“Blessed are the cracked, for they shall let in the light.”   Groucho Marx

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The smallest miracle right in front of you is enough to make you happy....

jrevens

Joined: 21 Nov 2013
Posts: 34
Location: Arvada, CO

Posted: Sat Nov 21, 2015 12:46 pm Post subject: Re: Rotax ignition wiring

 	  nuckolls.bob(at)aeroelect wrote: 	
		  At 09:12 PM 11/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "jrevens" <jrevens>



 This may be a dumb question, but would using a shielded twisted pair for the combined ignition control wiring to both modules be OK, or are 2 individual shielded single conductor wires preferred for some reason?  I am basically using Bob's Z-16 diagram... I am very grateful to have that, Bob! 	


   My pleasure. What you propose would be fine.

   Do you already have some twisted pair 20 or

   18AWG?



 

   Bob . . . 	




Yes I do, Bob. Not sure if I'll use it, but I was just trying to educate myself a little further in analyzing if there were any issues with using 2 wires enclosed in a common shield for this application. I like your suggestion to ground at the engine only and use the shield for the conductor back to the module.



Thanks to all for the replies.

_________________
John Evens
Thorp T-18 N71JE (sold)
Kitfox SS7 N27JE (built & flying)

jrevens

Joined: 21 Nov 2013
Posts: 34
Location: Arvada, CO

Posted: Sat Nov 21, 2015 1:08 pm Post subject: Re: Rotax ignition wiring

 	  rickofudall wrote: 	
		  All, The ignition modules and the pickups together cost almost $4,000 to replace. A few feet of shielded wire costs what, $1.49? I'd wire it exactly as Rotax says rather than experiment.



Rick Girard 	


Yep, those modules and pickups are really stupidly expensive and over-priced. I'm amazed that someone hasn't come up with a viable aftermarket replacement that could probably be sold for a fraction of the price and still make a nice profit.



I'm really not trying to "experiment" with this, Rick, but sometimes there is a little more elegant or simple way to do something that accomplishes the same result... maybe resulting in less weight, fewer connections, better design from a "noise" standpoint, etc. I'm not really convinced that doing everything "exactly as Rotax says..." is always the best that I can do. I've seen a couple of possible errors in their manuals for the 912 series engines. For instance, yesterday while studying the latest 912 Installation manual, I noticed the following on p.4 of section 80-00-00 regarding the starter system - "NOTICE - The starter relay must be isolated from the aircraft ground". What? I'm not sure if I'm misunderstanding that or what.

_________________
John Evens
Thorp T-18 N71JE (sold)
Kitfox SS7 N27JE (built & flying)

jrevens

Joined: 21 Nov 2013
Posts: 34
Location: Arvada, CO

Posted: Tue Nov 24, 2015 10:38 pm Post subject: Re: Rotax ignition wiring

Since there seem to be quite a few Rotax users on this forum, I have another question... is it really necessary to separate the wiring coming from the engine (pressure & temperature sensors, tachometer signal, etc). from the ignition (so called "p-leads") wires when penetrating the firewall. In other words, should the ignition wires have their own penetration, separated from that other wiring? I believe this is what Kitfox recommends. I hope this specific subject hasn't already been discussed on this forum.

_________________
John Evens
Thorp T-18 N71JE (sold)
Kitfox SS7 N27JE (built & flying)

user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Wed Nov 25, 2015 6:34 am Post subject: Re: Rotax ignition wiring

 	  Quote: 	
		  is it really necessary to separate the wiring coming from the engine 	


I have a Van's RV-12 registered as an E-LSA.  An E-LSA must be built exactly per the plans using only parts purchased from the manufacturer.  There are about 500 RV-12s flying with the Rotax 912.  All engine wires, including ignition, pass through one grommet in the firewall.

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Wed Nov 25, 2015 7:14 am Post subject: Rotax ignition wiring

On 11/25/2015 12:38 AM, jrevens wrote:

 	  Quote: 	
		   



 Since there seem to be quite a few Rotax users on this forum, I have another question... is it really necessary to separate the wiring coming from the engine (pressure & temperature sensors, tachometer signal, etc). from the ignition wires when penetrating the firewall. In other words, should the ignition wire have their own penetration, separated from that other wiring? I believe this is what Kitfox recommends. I hope this specific subject hasn't already been discussed on this forum.



 --------

 John Evens

 Thorp T-18 N71JE (built &amp; flying)

 Kitfox SS7 N27JE (building)



I can't directly address the Rotax question, but 'normal' practice when 
	


wires must be near each other that may hav interference issues is to 

have them cross at as close to 90 degrees as possible. The longer the 

parallel run, the more likely the interference. Might be worth a try to 

bundle the noise makers separate from the sensors, and try to make an 

'X' at the FW passthrough.



Charlie

rv10pro(at)gmail.com
Guest

Posted: Wed Nov 25, 2015 8:22 am Post subject: Rotax ignition wiring

Does this imply Van's would discourage buying a second pass - thru from them  and separating ignition wires from lower voltage signal wires.  What does Dynon say? 

Van's has always supported Safety of Flight issues to the best of my knowledge. 

John Cox On Nov 25, 2015 06:43, "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 

 > is it really necessary to separate the wiring coming from the engine

 

 I have a Van's RV-12 registered as an E-LSA.  An E-LSA must be built exactly per the plans using only parts purchased from the manufacturer.  There are about 500 RV-12s flying with the Rotax 912.  All engine wires, including ignition, pass through one grommet in the firewall.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=450208#450208

 

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Wed Nov 25, 2015 8:59 am Post subject: Re: Rotax ignition wiring

 	  Quote: 	
		  Does this imply Van's would discourage buying a second pass - thru from them  and separating ignition wires from lower voltage signal wires. 	


Van's will sell whatever a customer wants to buy.  Van's does discourage making changes to their designs.  USA government regulations require that aircraft registered as E-LSA be built exactly per the plans.  If a builder wanted to install two grommets for wires passing through the firewall, then the aircraft would have to be registered as E-AB, not E-LSA.  The majority of RV-12 are registered as E-LSA and are built according to the plans.  The point that I was trying to make is that it is OK to bundle all Rotax engine wires together because hundreds of RV-12s are flying with no electrical interference problems.  The Rotax has electronic ignition, not magnetos.  The Rotax ignition control circuit might not be high voltage like magneto control circuits.  I do not know.

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Joe Gores

rv10pro(at)gmail.com
Guest

Posted: Wed Nov 25, 2015 9:24 am Post subject: Rotax ignition wiring

Get with your intended DAR and ask about your "Must" understanding.  You might be pleasantly surprised with a safety improvement to boot.  I don't see the second pass-thru as a deal killer. 

John Cox On Nov 25, 2015 09:08, "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 

 > Does this imply Van's would discourage buying a second pass - thru from them  and separating ignition wires from lower voltage signal wires.

 

 Van's will sell whatever a customer wants to buy.  Van's does discourage making changes to their designs.  USA government regulations require that aircraft registered as E-LSA be built exactly per the plans.  If a builder wanted to install two grommets for wires passing through the firewall, then the aircraft would have to be registered as E-AB, not E-LSA.  The majority of RV-12 are registered as E-LSA and are built according to the plans.  The point that I was trying to make is that it is OK to bundle all Rotax engine wires together because hundreds of RV-12s are flying with no electrical interference problems.  The Rotax has electronic ignition, not magnetos.  The Rotax ignition control circuit might not be high voltage like magneto control circuits.  I do not know.

 

 --------

 Joe Gores

 

 

 

 

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 http://forums.matronics.com/viewtopic.php?p=450212#450212

 

 

 

 

 

 

 

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Posted: Wed Nov 25, 2015 9:26 am Post subject: Rotax ignition wiring

Once certificated E-LSA I would wager the modification would not invalidate your airworthiness and Not trigger a new Phase One. 

John Cox On Nov 25, 2015 09:08, "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 

 > Does this imply Van's would discourage buying a second pass - thru from them  and separating ignition wires from lower voltage signal wires.

 

 Van's will sell whatever a customer wants to buy.  Van's does discourage making changes to their designs.  USA government regulations require that aircraft registered as E-LSA be built exactly per the plans.  If a builder wanted to install two grommets for wires passing through the firewall, then the aircraft would have to be registered as E-AB, not E-LSA.  The majority of RV-12 are registered as E-LSA and are built according to the plans.  The point that I was trying to make is that it is OK to bundle all Rotax engine wires together because hundreds of RV-12s are flying with no electrical interference problems.  The Rotax has electronic ignition, not magnetos.  The Rotax ignition control circuit might not be high voltage like magneto control circuits.  I do not know.

 

 --------

 Joe Gores

 

 

 

 

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 http://forums.matronics.com/viewtopic.php?p=450212#450212

 

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Wed Nov 25, 2015 10:06 am Post subject: Re: Rotax ignition wiring

What safety improvement is achieved by drilling another hole through the firewall?

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Joe Gores

richard.beebe(at)yale.edu
Guest

Posted: Wed Nov 25, 2015 10:36 am Post subject: Rotax ignition wiring

Joe is correct that an E-LSA must be built exactly according to factory 

plans. However, once that's done it can be modified by the owner. If 

you're building the plane you can ask Vans if they would approve a 

second pass-thru. If so, then you can add it. If not, then you have to 

wait until after the plane is certified.



Vans is pretty safety conscious so I agree that if they don't have a 

problem running all the wires through a single pass-thru then I probably 

wouldn't either.



--Rick



On 11/25/2015 12:24 PM, John Cox wrote:

 	  Quote: 	
		   Once certificated E-LSA I would wager the modification would not

 invalidate your airworthiness and Not trigger a new Phase One.



 John Cox



 On Nov 25, 2015 09:08, "user9253" <fransew(at)gmail.com

 <mailto:fransew(at)gmail.com>> wrote:



     

     <fransew(at)gmail.com <mailto:fransew(at)gmail.com>>

      > Does this imply Van's would discourage buying a second pass -

     thru from them  and separating ignition wires from lower voltage

     signal wires.



     Van's will sell whatever a customer wants to buy.  Van's does

     discourage making changes to their designs.  USA government

     regulations require that aircraft registered as E-LSA be built

     exactly per the plans.  If a builder wanted to install two grommets

     for wires passing through the firewall, then the aircraft would have

     to be registered as E-AB, not E-LSA.  The majority of RV-12 are

     registered as E-LSA and are built according to the plans.  The point

     that I was trying to make is that it is OK to bundle all Rotax

     engine wires together because hundreds of RV-12s are flying with no

     electrical interference problems.  The Rotax has electronic

     ignition, not magnetos.  The Rotax ignition control circuit might

     not be high voltage like magneto control circuits.  I do not know.



     --------

     Joe Gores

gerry.vandyk(at)eastlink.
Guest

Posted: Wed Nov 25, 2015 10:54 am Post subject: Rotax ignition wiring

Have the rules for ELSA changed?  My understanding was, while a SLSA 

must conform to the manufacturer's specs throughout its life, after an 

ELSA has been registered and the test flying restrictions lifted, the 

owner is free to modify their ELSA as he sees fit, but it must continue 

to comply with LSA rules.



I reference these paragraphs from Kitplanes March 2012 "Understanding 

Experimental Light Sport Aircraft" by Dave Martin.  (The last 5 

paragraphs of the article.



"I've already alluded to an FAA ruling that makes it legal for the 

builder of an ELSA to make changes. In the case of a kit such as the 

RV-12, any change that does not take the aircraft outside of the LSA 

definition may be made as soon as the pink airworthiness certificate is 

signed by the FAA's inspector, usually a DAR. Mel Asberry, who writes 

the "Ask the DAR" column for this magazine, confirms the FAA's point 

that this feature has been in the plan from the beginning. Its rationale 

is that ELSA come under the same rules as any other 

Experimental-category aircraft.



"Some of us, myself included, missed this detail in our understanding of 

ELSA rules, and I found it to be a jaw-dropper. That's because no other 

Experimental-category aircraft is like a factory-approved ELSA. If I had 

built my RV-12 as an EAB, I could have modified it however I desired 

during construction. But as an ELSA, mine was required to be built 

initially exactly like the SLSA prototype.



"In addition to building, all testing was exactly as specified by Van's 

Aircraft. On the first five flights, I flew as a production test pilot, 

not as an experimental test pilot as I would in a new EAB. Also, if I 

had built the RV-12 as an EAB, the builder block on the data plate could 

read "Martin RV-12." Because my shop was a subset of the kit factory, my 

data plate lists Van's Aircraft Company as the builder.



"The result of this provision is that I could now change my airplane 

enough to cause it to operate quite differently—as long as it remains 

within the LSA definition. It's almost as if Piper and Cessna owners 

were allowed to make any changes they wanted.



"So this provision of ELSA remains, and it may explain the lack of ELSA 

kits competing with the Van's RV-12. Why should a company take on the 

additional liability of a customer making changes that are neither 

authorized nor tested by the factory?"



Gerry van Dyk



----

user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Wed Nov 25, 2015 3:44 pm Post subject: Re: Rotax ignition wiring

 	  Quote: 	
		  Have the rules for ELSA changed? 	


No, the rules have not changed and your understanding is correct.  Some builders have made modifications to their E-LSA RV-12 after certification.  And Van's has even adopted some of those mods.

  The originator of this thread asked if it is OK to bundle all engine wires together in his Rotax powered Kitfox.  I replied "yes" because that is the way that Van's designed the RV-12, which has the same engine.  If it is explained why bundling all engine wires together is unsafe, then I will change my wiring.

  I do not think that the Kitfox can be registered as an E-LSA.  So the Kitfox builder can wire his plane however he thinks is best.

_________________
Joe Gores

rv10pro(at)gmail.com
Guest

Posted: Wed Nov 25, 2015 10:38 pm Post subject: Rotax ignition wiring

The discussion point should center around "any" advantage of not bundling as a single penetration thru the firewall and the enhancements within E-LSA and the latitude if any to modify within the allowance by the chosen DAR. 

There are many DARs.  I have seen mods.  They make sense... In some cases.  That is what is great about Amateur built.  Happy Holidays! 

John Cox On Nov 25, 2015 15:50, "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 

 > Have the rules for ELSA changed?

 

 No, the rules have not changed and your understanding is correct.  Some builders have made modifications to their E-LSA RV-12 after certification.  And Van's has even adopted some of those mods.

   The originator of this thread asked if it is OK to bundle all engine wires together in his Rotax powered Kitfox.  I replied "yes" because that is the way that Van's designed the RV-12, which has the same engine.  If it is explained why bundling all engine wires together is unsafe, then I will change my wiring.

   I do not think that the Kitfox can be registered as an E-LSA.  So the Kitfox builder can wire his plane however he thinks is best.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=450301#450301

 

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Thu Nov 26, 2015 6:33 am Post subject: Re: Rotax ignition wiring

Happy Thanksgiving !

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