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Rotax 912 UL alternator drop-out
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paul.r.kuntz(at)gmail.com
Guest

Posted: Thu Aug 08, 2013 8:48 pm Post subject: Rotax 912 UL alternator drop-out

I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder.  The total electrical load with everything running is 7 to 8 amps.  Occasionally it can go to 9 or 10 amps if I'm charging cell phone and iPad en route.  I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.  



The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load.  The symptom was a voltage drop from 13.8 volts to 12.5 volts, which seemed strange.  On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts.  In flight, the voltage would drop to 12.5 volts and stay there for several minutes.  I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly.  I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.

  



The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel.  That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall. 

  



So the problem seems to be heat-related.  Does this make sense?  The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily.  Does the Ducati regulator have a thermal self-protect cutout?  Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?

  



Regards,

Paul Kuntz  

 

  [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Fri Aug 09, 2013 4:10 am Post subject: Re: Rotax 912 UL alternator drop-out

I have a RV-12 with Rotax 912 engine.  The voltage regulator can be damaged by excessive heat.  A fan that circulates warm air might not be enough.

  Van's Aircraft sells an aluminum shroud that is pop riveted to the fins of the voltage regulator.

Cooling Shroud part number F-00002 $10.

Blast Tube "DUCT CBT-5/8" connects to the Cooling Shroud.  $3.95 per foot.

http://www.vansaircraft.com/cgi-bin/store.cgi

See page 40-14 of this document for installation instructions:

http://www.vansaircraft.com/pdf/revisions/RV-12/Section_40.pdf

Joe

_________________
Joe Gores

paul.r.kuntz(at)gmail.com
Guest

Posted: Fri Aug 09, 2013 9:56 am Post subject: Rotax 912 UL alternator drop-out

Thanks for the tip.  I'll check this cooling shroud idea.  I'm also wondering if my regulator has already been compromised.  Any opinions on what my repeated fail/recover situation indicates?  I would guess that it cycled between failed and recovered 8 or 10 times before we established a state where it stayed on line, limited to a total current draw of 3 amps. 

Paul



On Friday, August 9, 2013, user9253  wrote:

[quote]--> AeroElectric-List message posted by: "user9253" <[url=javascript:;]fransew(at)gmail.com[/url]>

  

 I have a RV-12 with Rotax 912 engine.  The voltage regulator can be damaged by excessive heat.  A fan that circulates warm air might not be enough.

   Van's Aircraft sells an aluminum shroud that is pop riveted to the fins of the voltage regulator.

 Cooling Shroud part number F-00002 $10.

 Blast Tube "DUCT CBT-5/8" connects to the Cooling Shroud.  $3.95 per foot.

 http://www.vansaircraft.com/cgi-bin/store.cgi

 See page 40-14 of this document for installation instructions:

 http://www.vansaircraft.com/pdf/revisions/RV-12/Section_40.pdf

 Joe

 

 --------

 Joe Gores

 

 

 

 

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 http://forums.matronics.com/viewtopic.php?p=406294#406294

 

 

 

 

 

 

 

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klehman(at)albedo.net
Guest

Posted: Fri Aug 09, 2013 1:05 pm Post subject: Rotax 912 UL alternator drop-out

Paul



I would consider 12.5 volts to be a no charging situation but like you 

I'd also expect it to slowly drop further.

Your 13.8 volts is also pretty low to reasonably recharge a battery 

unless perhaps you are frequently flying long trips in hot temperatures. 

If you believe your voltmeter to be accurate, I'd indeed suggest a new 

regulator however the intermittent nature of the fluctuations could also 

indicate a poor connection.



The John Deere PM regulator is rated at 20 amps and has served me well 

(with a 20 amp alternator) on the cabin side of the firewall although 

mine is mounted on a bracket about a half inch from the firewall to let 

air circulate under it. I am not familiar with the rotax regulator but I 

would consider a unit that needs air blast on it in the cabin to be way 

too marginal for reliable service.



Ken



On 09/08/2013 12:46 AM, Paul Kuntz wrote:

 	  Quote: 	
		   I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to

 Oshkosh and back last week. The panel has a dual Dynon Skyview

 display with two-axis autopilot, plus radio and transponder.  The total

 electrical load with everything running is 7 to 8 amps.  Occasionally it

 can go to 9 or 10 amps if I'm charging cell phone and iPad en route.

   I'm pretty confident that I have the electrical system wired so that

 the ammeter is measuring the total electrical load.



 The alternator dropped out once on the outbound trip, but came back

 after removing the iPad charging load.  The symptom was a voltage drop

 from 13.8 volts to 12.5 volts, which seemed strange.  On preflight the

 voltage may read that high for a minute or so on a freshly-charged

 battery, but it quickly drops to 12.2 or 12.1 volts.  In flight, the

 voltage would drop to 12.5 volts and stay there for several minutes.  I

 would think that if the alternator had failed, I'd see the voltage drop

 to the same 12.1 volts that I see on preflight, and keep dropping

 slowly.  I can't see why it would drop to 12.5 volts and stay there,

 unless the voltage regulator is failing in a way that I'm not familiar with.



 The alternator dropped out (same symptoms) a few times on the trip back,

 but by reducing the load to 3 amps (one Skyview display, radio and

 transponder), it stayed on line except for awhile when it seemed that

 the mid-day sun shining on the dashboard was adding extra heat behind

 the panel.  That time we brought it back by directing cool air from a

 fresh air vent forward toward the spot where the voltage regulator is

 mounted inside the cabin on the back side of the firewall.



 So the problem seems to be heat-related.  Does this make sense?  The

 Rotax alternator is supposed to be rated for 18 amps, and able to handle

 a steady load of 14 amps easily.  Does the Ducati regulator have a

 thermal self-protect cutout?  Do I perhaps have a regulator that is

 ready to fail completely, or should I just put an avionics cooling fan

 behind the panel to get the air moving?Any other ideas?



 Regards,

 Paul Kuntz

pestar

Joined: 11 Apr 2007
Posts: 61
Location: Auckland, New Zealand

Posted: Fri Aug 09, 2013 2:38 pm Post subject: Re: Rotax 912 UL alternator drop-out

I own a French DynAero MCR-4S Rotax 914 which I part built in France prior to shipping back to New Zealand.  During this time I learnt that the standard Ducatti regulator was unreliable and so I never fitted it.  I replaced it with a GR6 Schicke electrical regulator which is an approved LAA mode in the UK for Rotax engines..



This regulator is a lot more robust and eliminates  the flakey issues you may be experiencing.  Mine is mounted under the co-pilots seat uncooled.



See http://www.sarangan.org/mhonarc/mharc/html//europa-list/2012-07/msg00009.html  and

http://www.lightaircraftassociation.co.uk/engineering/Standard%20Mods/SM12970%20Rotax%2091X%20Schicke%20GR6%20Regulator.pdf for further info.



Cheers Peter

_________________
Peter Armstrong
Auckland, New Zealand
DynAero MCR-4S (Do not shoot me Smile

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 09, 2013 3:12 pm Post subject: Rotax 912 UL alternator drop-out

At 11:46 PM 8/8/2013, you wrote:

I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to 

Oshkosh and back last week. The panel has a dual Dynon Skyview 

display with two-axis autopilot, plus radio and transponder.  The 

total electrical load with everything running is 7 to 8 

amps.  Occasionally it can go to 9 or 10 amps if I'm charging cell 

phone and iPad en route.  I'm pretty confident that I have the 

electrical system wired so that the ammeter is measuring the total 

electrical load.



The alternator dropped out once on the outbound trip, but came back 

after removing the iPad charging load.  The symptom was a voltage 

drop from 13.8 volts to 12.5 volts, which seemed strange.  On 

preflight the voltage may read that high for a minute or so on a 

freshly-charged battery, but it quickly drops to 12.2 or 12.1 

volts.  In flight, the voltage would drop to 12.5 volts and stay 

there for several minutes.  I would think that if the alternator had 

failed, I'd see the voltage drop to the same 12.1 volts that I see on 

preflight, and keep dropping slowly.  I can't see why it would drop 

to 12.5 volts and stay there, unless the voltage regulator is failing 

in a way that I'm not familiar with.



   Batteries charge at 13.8 and above, they deliver energy

   at 12.5 and below. Regulators are set to charge batteries

   so a functioning alternator produces a bus voltage generally

   above 14.0 volts.



The alternator dropped out (same symptoms) a few times on the trip 

back, but by reducing the load to 3 amps (one Skyview display, radio 

and transponder), it stayed on line except for awhile when it seemed 

that the mid-day sun shining on the dashboard was adding extra heat 

behind the panel.  That time we brought it back by directing cool air 

from a fresh air vent forward toward the spot where the voltage 

regulator is mounted inside the cabin on the back side of the firewall.



So the problem seems to be heat-related.  Does this make sense?  The 

Rotax alternator is supposed to be rated for 18 amps, and able to 

handle a steady load of 14 amps easily.  Does the Ducati regulator 

have a thermal self-protect cutout?  Do I perhaps have a regulator 

that is ready to fail completely, or should I just put an avionics 

cooling fan behind the panel to get the air moving?Any other ideas?



   How long has this regulator been in service? 10A is

   a pretty light load for a 912 regulator. I suspect

   something has become intermittent.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 09, 2013 4:26 pm Post subject: Rotax 912 UL alternator drop-out

At 05:38 PM 8/9/2013, you wrote:

 	  Quote: 	
		  



I own a French DynAero MCR-4S Rotax 914 which I part built in France 

prior to shipping back to New Zealand.  During this time I learnt 

that the standard Ducatti regulator was unreliable and so I never 

fitted it.  I replaced it with a GR6 Schicke electrical regulator 

which is an approved LAA mode in the UK for Rotax engines..



This regulator is a lot more robust and eliminates  the flakey 

issues you may be experiencing.  Mine is mounted under the co-pilots 

seat uncooled.


	


   Thanks for the heads-up Peter. I've heard a lot

   of complaints about the Ducatti regulators.

   There are certainly many examples of the technology

   with opportunity to out-perform the Ducatti product,

   Schicke and John Deere being amongst those that

   should be considered.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 09, 2013 4:29 pm Post subject: Rotax 912 UL alternator drop-out

At 12:55 PM 8/9/2013, you wrote:

 	  Quote: 	
		  Thanks for the tip.  I'll check this cooling shroud idea.  I'm also 

wondering if my regulator has already been compromised.  Any 

opinions on what my repeated fail/recover situation indicates?  I 

would guess that it cycled between failed and recovered 8 or 10 

times before we established a state where it stayed on line, limited 

to a total current draw of 3 amps.


	


   If your regulator can't carry 10A without cooling, it's

   probably broke. A functional part should be capable of

   rated output for the alternator which is on the order

   of 18A. I've not heard of any mass-movements to forced

   air cool these regulators.





   Bob . . .

paul.r.kuntz(at)gmail.com
Guest

Posted: Sat Aug 10, 2013 9:22 pm Post subject: Rotax 912 UL alternator drop-out

Thanks for the tips, everyone.  I concur with Bob that my Ducati regulator is done for and should be replaced.  I will take a look at the Schicke unit that Peter mentioned.



Cheers,

 Paul Kuntz



On Friday, August 9, 2013, Robert L. Nuckolls, III  wrote:

  [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

    

 At 12:55 PM 8/9/2013, you wrote:

  	  Quote: 	
		   Thanks for the tip.  I'll check this cooling shroud idea.  I'm also wondering if my regulator has already been compromised.  Any opinions on what my repeated fail/recover situation indicates?  I would guess that it cycled between failed and recovered 8 or 10 times before we established a state where it stayed on line, limited to a total current draw of 3 amps.

    	
 

   If your regulator can't carry 10A without cooling, it's

   probably broke. A functional part should be capable of

   rated output for the alternator which is on the order

   of 18A. I've not heard of any mass-movements to forced

   air cool these regulators.

 

 

 

 

   Bob . . . 

 

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paul.r.kuntz(at)gmail.com
Guest

Posted: Sat Aug 10, 2013 10:53 pm Post subject: Rotax 912 UL alternator drop-out

The plane has a total of 75 hrs; ditto the engine and electrical system, so it's all basically brand new.  The system voltage has always read 13.8 or 13.9 volts when the engine is running at normal flight RPMs, except for the drop-out periods I've described.  It may drop below 13 volts at low RPM on the ground, but I believe that's normal.  

 

I've never seen the load go above 12 amps. 9 or 10 amps seems like the normal load with everything running.  It's perhaps 2 amps less with the autopilot disengaged.  



The voltage regulator is on the cabin side of the firewall, mounted on a fairly large metal plate that stands off from the firewall about three-fourths of an inch.  The firewall is composite with an insulating asbestos (or similar) fire-resistant blanket on the engine side.  The cabin side never gets more than warm to the touch.  I agree with the replies that say the Ducati regulator should handle both the load and the environment fine with no additional forced air flow.  After reviewing all the replies, I'm inclined to just install a new one and see how it goes before I try to make changes to the system design, such as switching to a different regulator.  Seems like there should be plenty of head room in the existing system. 

 



Paul Kuntz 

On Friday, August 9, 2013, Robert L. Nuckolls, III  wrote:

[quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

  

 

 At 11:46 PM 8/8/2013, you wrote:

 I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to Oshkosh and back last week. The panel has a dual Dynon Skyview display with two-axis autopilot, plus radio and transponder.  The total electrical load with everything running is 7 to 8 amps.  Occasionally it can go to 9 or 10 amps if I'm charging cell phone and iPad en route.  I'm pretty confident that I have the electrical system wired so that the ammeter is measuring the total electrical load.

  

 The alternator dropped out once on the outbound trip, but came back after removing the iPad charging load.  The symptom was a voltage drop from 13.8 volts to 12.5 volts, which seemed strange.  On preflight the voltage may read that high for a minute or so on a freshly-charged battery, but it quickly drops to 12.2 or 12.1 volts.  In flight, the voltage would drop to 12.5 volts and stay there for several minutes.  I would think that if the alternator had failed, I'd see the voltage drop to the same 12.1 volts that I see on preflight, and keep dropping slowly.  I can't see why it would drop to 12.5 volts and stay there, unless the voltage regulator is failing in a way that I'm not familiar with.

  

   Batteries charge at 13.8 and above, they deliver energy

   at 12.5 and below. Regulators are set to charge batteries

   so a functioning alternator produces a bus voltage generally

   above 14.0 volts.

 

 The alternator dropped out (same symptoms) a few times on the trip back, but by reducing the load to 3 amps (one Skyview display, radio and transponder), it stayed on line except for awhile when it seemed that the mid-day sun shining on the dashboard was adding extra heat behind the panel.  That time we brought it back by directing cool air from a fresh air vent forward toward the spot where the voltage regulator is mounted inside the cabin on the back side of the firewall.

  

 So the problem seems to be heat-related.  Does this make sense?  The Rotax alternator is supposed to be rated for 18 amps, and able to handle a steady load of 14 amps easily.  Does the Ducati regulator have a thermal self-protect cutout?  Do I perhaps have a regulator that is ready to fail completely, or should I just put an avionics cooling fan behind the panel to get the air moving?Any other ideas?

  

   How long has this regulator been in service? 10A is

   a pretty light load for a 912 regulator. I suspect

   something has become intermittent.

 

 

 

   Bob . . . 

 

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 [b]

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Sun Aug 11, 2013 4:06 am Post subject: Re: Rotax 912 UL alternator drop-out

Since the problem is intermittent, it is more likely caused by a loose connection rather than bad electronics.  Prime suspect is the circuit going to voltage regulator pin "C", especially the controlling switch (Master ?) and wire terminals.

It would be a worthwhile test to monitor the voltage on pin "C" during alternator failure.

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 11, 2013 6:35 am Post subject: Rotax 912 UL alternator drop-out

At 07:06 AM 8/11/2013, you wrote:

 	  Quote: 	
		  



Since the problem is intermittent, it is more likely caused by a 

loose connection rather than bad electronics.  Prime suspect is the 

circuit going to voltage regulator pin "C", especially the 

controlling switch (Master ?) and wire terminals.

It would be a worthwhile test to monitor the voltage on pin "C" 

during alternator failure.


	


   Joe brings up a good point. Intermittent failures

   are more likely to be a loose connection as opposed

   to a misbehaving piece of electronics. The Ducatti

   regulators are potted, mechanically robust.

   Doing a study of ship's wiring integrity might save

   you from an unnecessary regulator change out.



   Bob . . .

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sun Aug 11, 2013 7:17 am Post subject: Rotax 912 UL alternator drop-out

This is especially true since your observed "full charging voltage" seems to

have always been a tad low. (max 13.9 volts when it would normally be

expected to be 14 or greater) 

This may also be indicative of a loose connection creating high resistance

and "fooling" the regulator right from the start. It may have never been

working optimally.



Bob McC.



 	  Quote: 	
		   

    Joe brings up a good point. Intermittent failures

    are more likely to be a loose connection as opposed

    to a misbehaving piece of electronics. The Ducatti

    regulators are potted, mechanically robust.

    Doing a study of ship's wiring integrity might save

    you from an unnecessary regulator change out.

 

 

 

    Bob . . .

_________________
Bob McC
Falco #908
(just starting)

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 11, 2013 8:53 am Post subject: Rotax 912 UL alternator drop-out

At 10:16 AM 8/11/2013, you wrote:

 	  Quote: 	
		  

<robert.mccallum2(at)sympatico.ca>



This is especially true since your observed "full charging voltage" seems to

have always been a tad low. (max 13.9 volts when it would normally be

expected to be 14 or greater)


	


    My recollection is that this series of regulators

    tend to run low in the spectrum of battery recharge

    protocols. My hypothesis is that the regulator is

    intended for use on consumer tools like garden tractors,

    machines that get used frequently in-season if not all

    year long. Consumers are not looking for optimum

    performance of a battery as an energy source, only

    long service life for engine cranking. So the low-end

    design point would tend toward that goal.



    Adding a voltage adjust pot would be pretty cool,

    but fraught with risk in the hands of the weekend,

    shade tree mechanic . . . so I think the Ducatti

    regulators are what they are for well considered

    reasons.



    Selection of this regulator by Rotax for use on an

    aircraft may be not so well reasoned.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Sun Aug 11, 2013 8:58 am Post subject: Re: Rotax 912 UL alternator drop-out

My Rotax voltage regulator also puts out 13.8 volts.  And so do others according to RV-12 owners that I have talked with.  The Rotax engine starts so quickly, usually within a couple of seconds, that the battery is never discharged.  Most of the time the regulator only needs to maintain the battery, not recharge it.

Joe

_________________
Joe Gores

rickofudall

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

Posted: Sun Aug 11, 2013 3:31 pm Post subject: Rotax 912 UL alternator drop-out

Bob, Or it may be that Ducati has a little of the Lucas bloodline.Let me tell you about my experience with another Ducati product used by Rotax. The ignition module used from approx 2005 until 2011, Rotax p/n 966726. It has a known failure in which it just stops firing at engine cranking speeds, but will fire at some elevated rpm. Once it is made to fire the module often resumes working properly for the rest of that day but when it is allowed to rest for a few days it resumes the high rpm firing. Case in point, a customers engine of that vintage that refused to start. We had already corrected a series of carburetor and fuel system issues and the engine still refused to start. I eliminated every possibility of ignition modules being grounded out, then removed them and contacted Lockwood Aviation. The customer sent the modules in and sure enough, on Lockwoods test stand they would not fire below 2000 rpm. Once that was reached the modules worked correctly then failed again in later tests.

 Rotax is offering owners of these modules a reduced price on the latest version, p/n 966727. This new module also offers a 'soft start' capability with a timed ignition retard to help the higher compression 912 ULS and S models start easier.

 



Rick Girard



On Sun, Aug 11, 2013 at 11:52 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>

  



 At 10:16 AM 8/11/2013, you wrote:

  	  Quote: 	
		   --> AeroElectric-List message posted by: Bob McCallum <robert.mccallum2(at)sympatico.ca (robert.mccallum2(at)sympatico.ca)>

 

 This is especially true since your observed "full charging voltage" seems to

 have always been a tad low. (max 13.9 volts when it would normally be

 expected to be 14 or greater)

 	
 



    My recollection is that this series of regulators

    tend to run low in the spectrum of battery recharge

    protocols. My hypothesis is that the regulator is

    intended for use on consumer tools like garden tractors,

    machines that get used frequently in-season if not all

    year long. Consumers are not looking for optimum

    performance of a battery as an energy source, only

    long service life for engine cranking. So the low-end

    design point would tend toward that goal.

 

    Adding a voltage adjust pot would be pretty cool,

    but fraught with risk in the hands of the weekend,

    shade tree mechanic . . . so I think the Ducatti

    regulators are what they are for well considered

    reasons.

 

    Selection of this regulator by Rotax for use on an

    aircraft may be not so well reasoned.

 

 

        Bob . . .

 

         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

 

 

 

 ====================================

 -List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ====================================

 http://forums.matronics.com

 ====================================

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ====================================

 

 

 

 



	




-- 

Zulu Delta

Mk IIIC

Thanks, Homer GBYM

It isn't necessary to have relatives in Kansas City in order to be unhappy.

   - Groucho Marx

 

  [quote][b]

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

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Aug 11, 2013 6:59 pm Post subject: Rotax 912 UL alternator drop-out

At 06:29 PM 8/11/2013, you wrote:

 	  Quote: 	
		  Bob, Or it may be that Ducati has a little of the Lucas bloodline.

Let me tell you about my experience with another Ducati product used 

by Rotax. The ignition module used from approx 2005 until 2011, 

Rotax p/n 966726. It has a known failure in which it just stops 

firing at engine cranking speeds, but will fire at some elevated 

rpm. Once it is made to fire the module often resumes working 

properly for the rest of that day but when it is allowed to rest for 

a few days it resumes the high rpm firing. Case in point, a 

customers engine of that vintage that refused to start. We had 

already corrected a series of carburetor and fuel system issues and 

the engine still refused to start. I eliminated every possibility of 

ignition modules being grounded out, then removed them and contacted 

Lockwood Aviation. The customer sent the modules in and sure enough, 

on Lockwoods test stand they would not fire below 2000 rpm. Once 

that was reached the modules worked correctly then failed again in later tests.

Rotax is offering owners of these modules a reduced price on the 

latest version, p/n 966727. This new module also offers a 'soft 

start' capability with a timed ignition retard to help the higher 

compression 912 ULS and S models start easier.



Rick Girard


	




   Interesting. I'm a little mystified by such stories.

   Seems to me robust electronics really isn't a difficult

   thing to do once you've set up design goals, written

   a test plan for performance issues critical to

   intended operation and then test and deliver to

   those issues.



   It's a cut-n-dried process; second nature for

   me and most of the electron-herders I've

   worked with. The fact that Rotax continues to ship

   a marginally adequate rectifier/regulator is also

   a puzzlement. I had a conversation with a system

   integrator a few weeks ago wherein he was wrestling

   with a constellation of noise generating components

   supplied with a new, fuel injected Rotax. The engine's

   fundamentals seem sound and of good value, yet the

   company persists in artificially crippling a good

   product with flaky accessories.



   It would be interesting to be a fly on the wall in

   some of their customer relations meetings that deal

   with reported field problems. I guess that presupposes

   that such meetings are even held.



   It would be VERY interesting to see a schematic

   and bill of materials for the problematic ignition

   module . . . and know how the design was changed

   to correct the problem! But it sounds like the

   recommended replacement wasn't a corrected design

   but a product with new features . . . while being

   free of the low rpm problems of the previous

   design. We'll never know . . .

   Bob . . .

rickofudall

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

Posted: Sun Aug 18, 2013 5:56 pm Post subject: Rotax 912 UL alternator drop-out

Paul, As an aside, if your Pipistrel is certificated as an SLSA you must get a Letter of Authorization from the factory to make any changes to the aircraft. If you don't, your airplane airplane's certificate of compliance becomes void. If the factory won't give you a letter, your only option is to remove the change or take the aircraft ELSA. 



Rick Girard



On Sun, Aug 18, 2013 at 10:57 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:

  	  Quote: 	
		  Several inputs suggested checking the connections on the leads coming from the alternator, and checking the system ground connections.  I checked the faston-type alternator lead connections, which were clean and tight.  I checked all of the ground connections, which were also tight.  Yesterday I went up for a test flight and confirmed the symptoms under varying system loads.  The normal system voltage with alternator on line is 13.8 volts, which is consistent with what others are reporting for the Rotax Ducati regulator.  I see a max load of 10 amps with everything running, so I am satisfied that the total load is well within the standard Rotax system capacity.  I also observed that the system voltage drops to 13.5 volts at the 10 amp max load, which seems abnormal.  Under this max load, the alternator dropped out after a few minutes, indicated by system voltage dropping to around 12.5 volts -- consistent with fully charged lead-acid battery.

  

When I reduced the load to 3 amps, which is my practical minimum (one Dynon display, radio and transponder), the alternator came back and stayed there, with system voltage at the normal regulator set point of 13.8 volts.  

  

I repeated this experiment a few times for various loads, finding that a total load above 5 or 6 amps will cause the alternator to drop out after a few minutes, and that it will come back when the load is reduced to 3 amps.  

  



I am pretty well convinced that my voltage regulator is bad.  I did learn from comments on this issue that Van's includes a voltage regulator cooling kit with its lighting kit for the RV-12, consisting of a length of plastic tubing that connects from the air intake duct to a shroud over the regulator, providing a direct blast of cooling air to counteract the increased electrical load of the lighting.  So there is certainly indication that the Ducati regulator is susceptible to overheating under load.  The RV-12 regulator is on the engine side of the firewall, however, and mine is on the cabin side.  At 10 amps with the regulator mounted in the cockpit environment, I'm thinking the regulator should be able to handle the load without supplemental cooling.  Others have noted the not-so-good reputation of the Ducati regulator,  but there are thousands of them in service on Rotax engines worldwide,  so rather than tackle a reconfiguration of my regulator and wiring  installation at this point , I ordered a replacement Ducati from  Lockwood Aviation and will see how it goes. I also ordered a overvoltage protection module from B&C, since the  Pipistrel electrical system does not include one.  I'll install it with  the new voltage regulator.

I'll report my findings after installing the new regulator.  



Paul Kuntz



On Sat, Aug 10, 2013 at 10:21 PM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:

   	  Quote: 	
		  Thanks for the tips, everyone.  I concur with Bob that my Ducati regulator is done for and should be replaced.  I will take a look at the Schicke unit that Peter mentioned.  



Cheers,

 Paul Kuntz



On Friday, August 9, 2013, Robert L. Nuckolls, III  wrote:

   	  Quote: 	
		  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

      

 At 12:55 PM 8/9/2013, you wrote:

  	  Quote: 	
		   Thanks for the tip.  I'll check this cooling shroud idea.  I'm also wondering if my regulator has already been compromised.  Any opinions on what my repeated fail/recover situation indicates?  I would guess that it cycled between failed and recovered 8 or 10 times before we established a state where it stayed on line, limited to a total current draw of 3 amps.

      	
 

   If your regulator can't carry 10A without cooling, it's

   probably broke. A functional part should be capable of

   rated output for the alternator which is on the order

   of 18A. I've not heard of any mass-movements to forced

   air cool these regulators.

 

 

 

 

   Bob . . . 

 

 ====================================

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 ====================================

 http://forums.matronics.com

 ====================================

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

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-- 

Zulu Delta

Mk IIIC

Thanks, Homer GBYM

It isn't necessary to have relatives in Kansas City in order to be unhappy.

   - Groucho Marx

 

  [quote][b]

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

paul.r.kuntz(at)gmail.com
Guest

Posted: Sun Aug 18, 2013 8:03 pm Post subject: Rotax 912 UL alternator drop-out

Correct, Rick, but mine is built from a kit and licensed as Experimental Amateur-Built, so I am not bound by the SLSA restrictions.  That's one of the main reasons I wanted to go the EAB route. 

 



Regards,

Paul



On Sun, Aug 18, 2013 at 6:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:

 [quote]Paul, As an aside, if your Pipistrel is certificated as an SLSA you must get a Letter of Authorization from the factory to make any changes to the aircraft. If you don't, your airplane airplane's certificate of compliance becomes void. If the factory won't give you a letter, your only option is to remove the change or take the aircraft ELSA.  



Rick Girard



On Sun, Aug 18, 2013 at 10:57 AM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:

   	  Quote: 	
		  Several inputs suggested checking the connections on the leads coming from the alternator, and checking the system ground connections.  I checked the faston-type alternator lead connections, which were clean and tight.  I checked all of the ground connections, which were also tight.  Yesterday I went up for a test flight and confirmed the symptoms under varying system loads.  The normal system voltage with alternator on line is 13.8 volts, which is consistent with what others are reporting for the Rotax Ducati regulator.  I see a max load of 10 amps with everything running, so I am satisfied that the total load is well within the standard Rotax system capacity.  I also observed that the system voltage drops to 13.5 volts at the 10 amp max load, which seems abnormal.  Under this max load, the alternator dropped out after a few minutes, indicated by system voltage dropping to around 12.5 volts -- consistent with fully charged lead-acid battery.

   

When I reduced the load to 3 amps, which is my practical minimum (one Dynon display, radio and transponder), the alternator came back and stayed there, with system voltage at the normal regulator set point of 13.8 volts.  

   

I repeated this experiment a few times for various loads, finding that a total load above 5 or 6 amps will cause the alternator to drop out after a few minutes, and that it will come back when the load is reduced to 3 amps.  

   



I am pretty well convinced that my voltage regulator is bad.  I did learn from comments on this issue that Van's includes a voltage regulator cooling kit with its lighting kit for the RV-12, consisting of a length of plastic tubing that connects from the air intake duct to a shroud over the regulator, providing a direct blast of cooling air to counteract the increased electrical load of the lighting.  So there is certainly indication that the Ducati regulator is susceptible to overheating under load.  The RV-12 regulator is on the engine side of the firewall, however, and mine is on the cabin side.  At 10 amps with the regulator mounted in the cockpit environment, I'm thinking the regulator should be able to handle the load without supplemental cooling.  Others have noted the not-so-good reputation of the Ducati regulator,  but there are thousands of them in service on Rotax engines worldwide,  so rather than tackle a reconfiguration of my regulator and wiring  installation at this point , I ordered a replacement Ducati from  Lockwood Aviation and will see how it goes. I also ordered a overvoltage protection module from B&C, since the  Pipistrel electrical system does not include one.  I'll install it with  the new voltage regulator.

I'll report my findings after installing the new regulator.  



Paul Kuntz



On Sat, Aug 10, 2013 at 10:21 PM, Paul Kuntz <paul.r.kuntz(at)gmail.com (paul.r.kuntz(at)gmail.com)> wrote:

    	  Quote: 	
		  Thanks for the tips, everyone.  I concur with Bob that my Ducati regulator is done for and should be replaced.  I will take a look at the Schicke unit that Peter mentioned.   



Cheers,

 Paul Kuntz



On Friday, August 9, 2013, Robert L. Nuckolls, III  wrote:

   	  Quote: 	
		  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

       

 At 12:55 PM 8/9/2013, you wrote:

  	  Quote: 	
		   Thanks for the tip.  I'll check this cooling shroud idea.  I'm also wondering if my regulator has already been compromised.  Any opinions on what my repeated fail/recover situation indicates?  I would guess that it cycled between failed and recovered 8 or 10 times before we established a state where it stayed on line, limited to a total current draw of 3 amps.

       	
 

   If your regulator can't carry 10A without cooling, it's

   probably broke. A functional part should be capable of

   rated output for the alternator which is on the order

   of 18A. I've not heard of any mass-movements to forced

   air cool these regulators.

 

 

 

 

   Bob . . . 

 

 ====================================

 -List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ====================================

 http://forums.matronics.com

 ====================================

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ====================================

 

 

 

 	
 

 



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	
	




-- 

Zulu Delta

Mk IIIC

Thanks, Homer GBYM

It isn't necessary to have relatives in Kansas City in order to be unhappy.

    - Groucho Marx

 

   	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	
[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 19, 2013 6:52 pm Post subject: Rotax 912 UL alternator drop-out

 	  Quote: 	
		     I see a max load of 10 amps with everything running, so I am 

 satisfied that the total load is well within the standard Rotax 

 system capacity.  I also observed that the system voltage drops to 

 13.5 volts at the 10 amp max load, which seems abnormal.  Under 

 this max load, the alternator dropped out after a few minutes, 

 indicated by system voltage dropping to around 12.5 volts -- 

 consistent with fully charged lead-acid battery.


	


   The symptoms you observed suggest a temperature sensitive

   failure mode within the regulator . . . like a connection

   that opens when the regulator warms up. While a cooling

   system MIGHT mask this failure, it wouldn't necessarily

   be a case of overheating beyond rated operating temperatures

   rather a case of an intermittent connection that is

   temperature sensitive.



   Bob . . .

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