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Regulator Failure on Van's Demo RV-12

todehnal

Well Known Member
I happened to notice the voltage regulator being replaced on Van's demo RV-12 at the Mt. Vernon Illinois Light Sport Expo yesterday. It must be nice to be able to get a overnight shipped replacement unit with a phone call to your Oregon support team. By the way, it was mounted in the recently suggested location under the Avionics panel. Apparently this location is still not a satisfactory fix. My guess is that the fix is more complicated than just moving the regulator. How are you guys doing who have replaced your original Ducati with the Silent Hektik design? Too bad they are so hard to get, and the cost is so high; nearly $300 shipped from a motorcycle dealer in England.

Tom
 
New

Do you know if the replacement is the Ducati regulator?

I know rotax has moved away from that regulator with the is sport.

Leo
 
I installed Sikent Hektik in the original location, but with an aluminium plate as a heat screen between the close exhaust pipe. 30 minutes job.
I have blown three Ducatis in 650 hours.
SH has a charge voltage of 14.1 volts so I have moved the alarm limit to 14.2 in the Dynon.
SH advises to install a separate awg16 ground from the case to battery minus.
Whilst the Ducatis get extremely hot the SH is not even warm.
Feels so much better.
We pay $ 220 incl shipping but we are next door
 
Rotax regulator

I don't have a part number or manufacturer but this is what I got from the Canadian Rotax dealer when I inquired about the regulator(s) on the IS Sport:
"They are a German made regulator, not Ducati. They do need cooling air; more so on the 30 amp, but the RV12 has good airflow in the cowl so it should not be a problem."

I should also mention that the sport comes standard with a 16 and 30 amp alternator, each have their own regulators.

Leo

Yes it was the same Ducati that we have been using. So, what is Rotax using now?
 
We have two RV12s and at a total of about 1000 hours I have a box of 5 blown regulators.
We load about 15 to 16 Amps with two Sv1000 units and all other stuff.
The ducatis run at 175 deg F at this load which is close to the limit.
We monitor the temp by a sensor.
This working temperature degrades the lifetime as we found.

The SH can handle 47 Amps and has more efficient switching thus less losses and heat generation. We measured about 120 deg F.
We only have a short track record but at this temperature I have faith.

I am surprised Rotax is not offering an alternative at so many failures in so many years.
 
I happened to notice the voltage regulator being replaced on Van's demo RV-12 at the Mt. Vernon Illinois Light Sport Expo yesterday. It must be nice to be able to get a overnight shipped replacement unit with a phone call to your Oregon support team.

Maybe nice, but that is not how he got a replacement. (see THIS post)

BTW, Van's has been flying RV-12's far from home base for about 10 years now and this is the first time that I can remember there being an electrical / voltage regulator problem that had to be repaired away from home.
 
Gents, it was Friday and ANY other RV builder/pilot could have had any part overnighted to them. Personally, I think the support from the RV comunity and the Factory is superb, and it has been witnessed many times before on this forum. I was so happy to be a recipient of both this week as there were potential customers that I did not want to let down due to a grounded aircraft.

I know there have been regulator failures out there. I've seen them on other airplanes besides the RV12 as well. This particular RV-12 has over 450 hours on it and it is the first failure as far as I can tell. Quite honestly, demo aircraft are really hard on batteries and electrical components such as regulators, as there are a lot of start-ups, taxiing, and short flights which really max out the regulator and don't exactly allow time for the battery to accept a full charge. Especially at these expos, with a busy traffic pattern, the taxi and hold time is usually at such low rpm's that the battery is sitting there discharging while it is carrying the electrical load.

Vic
 
Maybe nice, but that is not how he got a replacement. (see THIS post)

BTW, Van's has been flying RV-12's far from home base for about 10 years now and this is the first time that I can remember there being an electrical / voltage regulator problem that had to be repaired away from home.

Thanks Scott and Vic. Things were a bit hectic at the expo while Vic was making the regulator swap. Here was a guy feverishly working to get his RV-12 ready to fly so he could beat Hurricane Irma back to Georgia, and safely put away, and I really felt bad for him. Vic mentioned that he received the regulator overnight, and i presumed that it was from you folks in Oregon. My bad! You guys are right, there is nothing better than the support that comes from everyone associated with the Van's aircraft family, and I say that with personal experience. I guess the frustrations level rises when you see all of these Ducati regulator failures. No one can honestly say that this is not a weak point that needs attention. Hoping for a permanent fix some day. ........Tom
 
As far as I know, the tractor regulator I put in my -12 is still going strong in the Texas heat 300 hours later.
 
As far as I know, the tractor regulator I put in my -12 is still going strong in the Texas heat 300 hours later.

Likewise, Ducati VR failed at 100TT and was replaced with John Deere AM101406 - does nice job maintaining battery voltage at 14V.

VR mounted on firewall shelf in original location with new 1/8" aluminum sub base for heat dissipation. Used heat transfer paste at the VR / sub plate.

Now 280TT and going strong. I don’t like electrical failures, so I have a 2nd JD on the shelf for $27.99 free shipping from eBay.
 
Regulator failures

The Ducati regulator is a marginal unit both from an electrical design, thermal design and mechanical design viewpoint. A friend with a RV-12 had a Ducati regulator fail within the first 40 hr of flight time. I carefully took the unit apart to determine the cause of failure and determine the circuit configuration.
The circuit uses a bridge rectifier configuration with two SCRs in opposing legs of the bridge. The firing angle of the SCRs is varied as the output voltage of the generator winding changes with engine rpm and electrical load to provide the regulated output. The SCRs used in the unit I took apart have a very high saturation voltage ( based on the data sheet for the part) so the efficiency of the unit and consequential thermal losses would result in high unit temperatures. The design of the control circuit is almost identical to a readily available circuit schematic available on the web. Ciruit component values were a little different but the topology was the same. The thermal design and mechanical design were very poor. Both SCRs and one power diode in the bridge had failed in a short circuit mode typical of an over temp condition. Analysis of the control circuit showed that not getting a good 12 volt reference could result in unstable operation of the regulator and induce premature failure. The airplane wiring schematic shows the 12 volt reference to the regulator going through a large number of connections to go from the master relay to the regulator. The regulator was replaced and the 12 volt reference wired directly from the master relay to the regulator. The location of the regulator on the engine side of the firewall was left the same. So far the second regulator has over 120 hr and 12 months of operation without failure. The Ducati regulator is truly a weak link in the electrical system for the RV-12. I was hoping there would have been a robust alternative by this time.
 
Regulators

Another consideration when swapping out the Ducati regulator for some other alternative.
The engine alternator windings are in the same magnetic circuit as both ignition circuit generator windings. So theoretically saturation of the generator magnetic circuit could result in no voltage to the two ignition circuits and engine stoppage. I dont know if this is a practical possibility - would very much depend on the tightness of the magnetic coupling and the saturation characteristics of the engine generator. Since it is unlikely that Rotax would provide any electrical design data on which to base a more detailed analysis the only way to be sure that a regulator failure couldnt take out the ingnition circuit would be through extensive testing
Just a concern about using any new regulator without detailed analysis and testing.
 
Cold solder joint

Out of curiosity I took apart the failed regulator to understand the root cause. It was a cold solder joint on a large wire on the printed circuit board. Clearly the board is wave soldered and that might not be the best for large wire protrusions. I had to use a Weller 100W soldering iron to get it to form a good solder joint, and then I tested it on the aircraft.
Worked like a champ, with 13.7 volts right at startup and solid battery charge of 5 amps and decreasing (meaning the battery was completing its charge). Prior to that I had 11.5 volts showing on the battery and -6 amps discharge.

Vic
 
. . . . the 12 volt reference wired directly from the master relay to the regulator.
The disadvantage of doing that is that there is no way to shut off electrical power in case of smoke in the cockpit. Shutting off the master contactor will not shut down the charging system because the "C" terminal will still be energized by the regulators output. I know because I experimented. When wired per above, everything kept right on working when the master switch was shut off, although the voltage was unstable, varying plus and minus about a volt or so, setting off the Dynon high voltage alarm.
 
Simply order the VR directly from the manufacturer. According to their web site they ask
? 165.- (excl. tax) for it
https://www.silent-hektik.de/UL_R_912.htm

Yeah, that's easy for you, living in Switzerland. I emailed them and they do not ship to the USA. That means that we have to order through a 3rd party, and the only source I could find was a Moto Guzzi dealer in Europe who does ship to the USA. That is where the $300 US quote came from. Lucky you!

Tom
 
I happen to be flying a Kitfox at the moment, but since I have the same engine, a Rotax 912 ULS, I like to monitor your forum; it has lots of good Rotax info.

I too lost a regulator. I replace it with a NAPA SME 7068102.

My regulator is inside the cockpit and I mounted a 5" 12 volt cooling fan that blows directly on the regulator. Wired it into the master switch, so anytime the power is on, the cooling fan is running. Have flown well over 100 hours now with no further issues. Puts out 14.7 volts and will handle up to 20 amps.

I think it's important to keep these regulators as cool as possible; the dedicated cooling fan seems to be working well.

I got the idea for using this regulator from this forum; there is a good thread on here that recommended the NAPA regulator.

Regards
Rodney
 
I don't have a part number or manufacturer but this is what I got from the Canadian Rotax dealer when I inquired about the regulator(s) on the IS Sport:
"They are a German made regulator, not Ducati. They do need cooling air; more so on the 30 amp, but the RV12 has good airflow in the cowl so it should not be a problem."

I should also mention that the sport comes standard with a 16 and 30 amp alternator, each have their own regulators.

Leo

Is the (apparently new) regulator used on the IS Sport compatible to retrofit to the older engines?
 
I have been using the alternative Amazon regulator for 100 hrs. with a small 2 inch wide fan blowing directly on the fins also. It is working great. I just piggybacked the hot wire for the fan to B+ wire on the regulator. It switches on and off with the master.
 
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I have been using the alternative Amazon regulator for 100 hrs. with a small 2 inch wide fan blowing directly on the fins also. It is working great. I just piggybacked the hot wire for the fan to B+ wire on the regulator. It switches on and off with the master.

Hey Dave, which regulator is that from Amazon? Also, you might be interested to know this week I am doing a transition training for the newest owner of N588DF.

John
 
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