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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FastEddieB
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ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Tue Oct 25, 2016 5:21 pm

I went to fly yesterday and on engine start my GEN light stayed on.

My first suspect was the multi-pin connector going to the Ducati voltage regulator - at least twice before that's been the culprit, once with corrosion due to water incursion and once due to the minor burning mentioned below.

I had a heck of a time getting the plug out. When I did, this is what I found:

Image

I had seen minor burning before on one of those pins, but nothing like this. You can even see a little blob of solder in the photo above, and the male connector was ever-so-slightly deformed in that area, which is what made it hard to pull out.

A fellow at the airport thought a loose spade connector in the multi-pin plug could be the culprit, with the bad connection leading to the high resistance and resultant heat.

Long story short, I cleaned everything up as best I could with a wire brush, applied some Stabilant-22, reinstalled and the problem is fixed, at least for now.

I happen to have a spare plug, and I think replacing mine would be wise. I would have done it yesterday, but did not have the right crimping tool at hand.

Any thoughts? Anything to look out for when crimping the new spade connectors?

Thanks in advance.
Fast Eddie B.
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David
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby David » Tue Oct 25, 2016 6:25 pm

From the VAF RV12 section, there is a lot of talk about the John Deere Regulator if you do need to replace it.
http://www.vansairforce.com/community/showthread.php?t=122197&highlight=John+deere&page=24
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Tue Oct 25, 2016 7:08 pm

David wrote:From the VAF RV12 section, there is a lot of talk about the John Deere Regulator if you do need to replace it.
http://www.vansairforce.com/community/showthread.php?t=122197&highlight=John+deere&page=24


Well, THAT certainly piqued my interest!

Just getting away from that multi-pin connector would help simplify things.
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Tue Oct 25, 2016 7:41 pm

Eddie,
This usually happens when the plug ends are not fully pushed into each other. Then there is arcing. Many times it may take two hands to fully seat all the connectors in the plug.

p.s.
Vans has the highest VR failure rate among all aircraft MFG's. They have a problem, but don't seem to be working very hard to figure it out. One of the best things to do with the RV12 is move the VR off that hot metal shelf right behind the really hot #4 exhaust pipe. I know they had a bulletin to move it inside, but few did it. Another help would be to turn the hose that is supposed to help with cooling in the air intake towards the opening of the larger tube. This will force cool air over the VR. Having it sit sideways in the tube causes a suction and that just draws more hot air over an already hot VR. The VR is covered with a metal box lid so unless the air is a forced draft type the VR can't get rid of the heat. VR's also build excessive heat if there is too much or too little draw on them.
Roger Lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Tue Oct 25, 2016 7:48 pm

roger lee wrote:Eddie,
This usually happens when the plug ends are not fully pushed into each other. Then there is arcing. Many times it may take two hands to fully seat all the connectors in the plug.


Thanks.

It sure seemed like the plug was fully seated - the little locking tabs were both secured.

But I'll be sure to double-check.

In a typical installation, are all 6 lugs used? I ask because the John Deere that David mentioned only seems to have 5 lugs.
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Wed Oct 26, 2016 3:00 pm

Buttoned things up today.

Here's my old voltage regulator and associated new plug:

Image

GIALLO = Yellow
ROSSO = Red
CHIAVE = Key (?)
BATT & LAMP should be self-explanatory

As an aside, I came across this from the Vans Air Force site when I did a Google Image search:

Image

So apparently mine is not a unique case.
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Thu Oct 27, 2016 8:49 am

This is usually from the connectors not being properly seated and then it arcs. You must always make sure the plug is seated all the way in and that when you pull on the wires they don't come out. This is rarely every the engine cause, but an owner caused issue. Squeeze them plugs in tight and two hands is best.
Roger Lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Thu Oct 27, 2016 11:40 am

roger lee wrote:This is usually from the connectors not being properly seated and then it arcs. You must always make sure the plug is seated all the way in and that when you pull on the wires they don't come out. This is rarely every the engine cause, but an owner caused issue. Squeeze them plugs in tight and two hands is best.


Lord knows, as an owner I've caused my share of issues, so I don't want to come across as knee-jerk defensive, but...

My plug was quite firmly seated. There are locking tabs that should ensure proper seating, and both were engaged. In fact, the plug was seated beyond where the tabs engaged. As I said, it was so firmly seated it was difficult to get out.

I'll buy that the female spade lugs may have loosened up over time, causing arcing and heat. But not owner error in this case.

Also, what are the chances that the voltage regulator is in fact failing internally, causing the heat, rather than just a connection issue?
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Thu Oct 27, 2016 3:45 pm

If those are the two yellow wires (G & G on the plug) those are the AC input from the back of the engine. The VR wouldn't have any influence up to these two connectors. The AC current would just be entering the VR.
Roger Lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby howardnmn » Sat Oct 29, 2016 11:34 am

Ohm's Law

this may not sound relevant but...for those having ducati VR issues on Rotax 20A alternator, buy a new battery with more energy storage. I used a higher capacity LiFePO4 to solve problem.

when electrical system makes large demands during low output -- for example on approach when landing w/ lights & radios on and engine at idle -- the voltage drops. So this causes current to increase to provide enough power. Excessive Current causes VR/connector to fail. If battery big enough voltage doesn't drop so much during this short period of high demand when output from Alternator is very low (much lower than 20A nominal rating)
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Nomore767 » Sat Oct 29, 2016 8:59 pm

My Ducati VR failed on take-off today.

With 282 hours on my RV-12 SLSA I've done better time wise than many others. There is an SB out from Vans to permit relocation of the VR which currently sits close behind the exhaust from an engine cylinder.

I'm currently thinking of simply replacing until I get the time for my Rotax guy to get the kit to relocate ( under the right side of instrument panel).

Frustrating, especially during the great flying weather in SC!

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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Sun Oct 30, 2016 12:28 am

Van's RV12's have the highest VR failure rate for any MFG. If it is still mounted on the metal shelf behind the #4 exhaust pipe you should move it. If it has already been moved then Vans still has an electrical issue on top of the heat issue. I have never seen or heard of as many failures as Vans has.
Roger Lee
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby FastEddieB » Sun Oct 30, 2016 7:43 am

Nomore767 wrote:My Ducati VR failed on take-off today.

With 282 hours on my RV-12 SLSA I've done better time wise than many others. There is an SB out from Vans to permit relocation of the VR which currently sits close behind the exhaust from an engine cylinder.

I'm currently thinking of simply replacing until I get the time for my Rotax guy to get the kit to relocate ( under the right side of instrument panel).

Frustrating, especially during the great flying weather in SC!


Going forward, even short term, might wrapping your exhaust cut way down on the temps the VR is exposed to?
Last edited by FastEddieB on Sun Oct 30, 2016 9:25 am, edited 1 time in total.
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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby Nomore767 » Sun Oct 30, 2016 9:19 am

Roger and Eddie,

Short term replacing the VR in its current location gets me flying and is relatively simpler for the ' regular' shop on my airfield. That gets me flying so that I can get to my Rotax IA/A&P light sport mechanic whereby we can complete the relocation to the spot suggested in the Vans SB.

My plane is SLSA so I have to follow those rules. Actually, not even sure that Vans approves wrapping the exhaust and I don't know enough to say either way.

From the VAF site Roger is right about the disproportionate number of VR failures in RV-12s all likely because of the poor location.

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Re: ROTAX/Ducati Voltage Regulator Connector Issue

Postby roger lee » Sun Oct 30, 2016 11:15 am

Vans has an LOA out to move the VR out of the engine compartment into the cabin. This would help. What would be better and I have done a few is to as Eddie suggest wrap all 4 exhaust to cut way back on radiated and convected heat and to take the small 1" air tube that is mounted in the air intake and point it forward to get cool forced air over the VR. The way that tube is now very little air flow occurs and it is more a suction because the air flowing past it causes a low pressure at that opening and then down at the VR that is already covered with a metal box allows very little air movement and what does move is only hot air off #4 exhaust pipe. Turning the hose into the air stream forces cool air over the reg. I just siliconed these facing forward. You could if you wanted use a wire tie throught the tube to hold it in place.
When I put a temp strip on it it dropped the temps by more than 30F.


If eliminating all heat source issues fail to work with Vans then a electrical check may be in order for them.
Roger Lee
Tucson, Az.
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