ROTAX/Ducati Voltage Regulator Connector Issue

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

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Merlinspop
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Merlinspop » Sun Nov 06, 2016 9:46 am

roger lee wrote:"leads to premature failure of the exhaust system".

......

p.s.
feel free to repost this on the Vans site.

Think he'll get banned if he does?
- Bruce

Nomore767
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Nomore767 » Sun Nov 06, 2016 10:13 am

roger lee wrote:"leads to premature failure of the exhaust system".

This isn't true. Many people have wrapped Rotax exhaust. I have been wrapping them for 12 years without a single issue. They just don't have any real time experience so they are over cautious. Flight Design did with with a fleet approval and it has helped many and they have not had any issues. These exhaust are stainless steel and are not susceptible to the heat or carbonization that plain steel is because of the chrome and nickel content. It prevents up to 70% heat reduction from radiated and convected heat. It helps save wire insulation, rubber engine mounts and hose from early degradation. Overheating can only come from improper application. You are only supposed to over wrap each edge by 3/8", but if you overwrapped by 1/2 the width or by 1" then the pipe could retain too much heat. There are RV12's out there that are using the wrap. I know, I put it there. It will not cause failures when you apply it correctly and with all the owners with wrapped exhaust it's very easy to prove.
Living in denial that they have an issue and not ACTIVELY addressing it just causes owners more grief and money when a fix is so simple.

p.s.
feel free to repost this on the Vans site.


Roger
Thanks for the info. I don't doubt what you say.

I asked Vans Tech Support directly about this and posted their opinion above. As I am SLSA and bound by that I don't have the option. That said if the VR is moved to the cabin side of the firewall then isn't wrapping the exhaust now moot?

How many SLSA Rotax exhausts have you wrapped or seen wrapped? My plane is #38 SLSA and I'm not sure what they're up to now.

Thanks for the points you made.

EDIT : I looked at the FAA Register and they have 99 SLSAs on it.

roger lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Sun Nov 06, 2016 3:26 pm

Most all have been SLSA. I tried to post some fleet approvals and pics for you, but this site wouldn't let me. I may alter the approvals to a different format and try again. I bet I know of at least 100 Rotax engines with wrap at least 3/4 of them are SLSA. There is no downside here. It cuts heat in the engine compartment to everything.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Mon Nov 07, 2016 12:24 am

There is a picture by Jetguy on the Vans forum of the wrong way to wrap an exhaust pipe. It is way over wrapped and will cause excessive heat. You should use 2" wide wrap and ONLY OVERWRAP BY 3/8" as you spiral down.
I tried to post that picture here, but this site still won't allow it. His picture shows some discoloration on the pipe which is no big deal. It is from moisture.

http://www.vansairforce.com/community/s ... p?t=143446
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

Nomore767
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Nomore767 » Mon Nov 07, 2016 8:06 am

Thanks Roger

I saw. The pics and can see what you mean about the overlap. The moisture stain you point out looks a bit like rust.

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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Mon Nov 07, 2016 9:03 am

There are 18 types of stainless steel. Some have more chrome and nickel compared to others. You need to pick which works best for a particular application. The lower of the two may allow some surface discoloration, but in all my years I have never seen or had anyone ever tell me the wrap has been a problem. I have seen some broken pipes (no wrap), but most of those are cause by poor stress relief during welding which isn't done at Rotax. I have seen this discoloration on many exhaust and it isn't an issue. I have seen some Rotax exhaust that have been wrapped for more than 20 years and tons of them for more than twelve years.
Some say you can't see if a pipe starts to break under the wrap. That's another myth. If one of these stainless pipe breaks it snaps all the way across and shreds the wrap. You'll have no question about it. This is why you actually do not need to remove the wrap at annaul to inspect. Any leak will trash the wrap. It is fragile once burned in place.

Here are some pics of the right way.

http://ctflier.com/index.php?/topic/400 ... -pictures/

http://ctflier.com/index.php?/topic/281 ... p-picture/
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

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MrMorden
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby MrMorden » Mon Nov 07, 2016 2:34 pm

Coming back from the CT fly-in in Arizona last year, I had a pretty spectacular exhaust failure. The #3 exhaust pipe was literally broken in half at a weld, and there were spiderweb style cracks all through the side of the muffler from where the exhaust pipe attaches to it. I have posted pics elsewhere on this forum, but can re-post if folks want to see the damage. Luckily I found it on preflight (remove the cowling if about to go on a long cross country flight!), and Roger found me a great stainless steel welder who got me back in the air the next morning.

I don't think wrapping could possibly cause issues. What damages exhausts are poor factory welds (I think this was part of my issue), excess heat, and vibration. Heat should be normal on a Rotax unless something is crazy wrong to cause high EGTs. With no mixture control there's not really anything you can do about high EGTs anyway other than check your plugs and mixture/carb/float settings on the ground.

That leaves vibration, which is probably the largest culprit. Keep your carbs in good sync, get your prop balanced, and make sure engine mount isolators and exhaust springs are in good shape. Those things will have a far greater impact on exhaust health than whether or not the pipes are wrapped. Is sounds like Van's is trying to take a Lycoming issue and translate it over to Rotax, which is a very different engine and exhaust setup.
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Mon Nov 07, 2016 8:15 pm

These are stainless pipes and any small amount of moisture has never hurt any yet.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

Wm.Ince
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Wm.Ince » Mon Nov 07, 2016 11:26 pm

MrMorden wrote:. . . "
That leaves vibration, which is probably the largest culprit. Keep your carbs in good sync, get your prop balanced, and make sure engine mount isolators and exhaust springs are in good shape. Those things will have a far greater impact on exhaust health than whether or not the pipes are wrapped." . . .


Concur with everything Andy mentioned.
Additionally, I suggest avoiding engine RPM ranges which create more vibration, such as idling at very low RPM, during ground operations. Personally, my engine idles at 1750-1800 RPM (warmed up) and that results in minimal vibration and smooth operation. What's more, I think it is much better on the gearbox.
Bill Ince
CTSW
Retired Heavy Equipment Operator

roger lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Tue Nov 08, 2016 8:15 pm

Here are pictures of what happens when an exhaust pipe breaks and why header wrap won't hide the issue and the extra noise. Pipes usually break to poor stress relief during welding and improper spring tension which allows too much vibration.

http://ctflier.com/index.php?/topic/400 ... -cracking/
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

Nomore767
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Nomore767 » Wed Nov 09, 2016 4:15 pm

Today I flew my RV-12 with the new and relocated Voltage Regulator. Everything went well and the mechanic did a nice job.


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