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Odd Occurrance - Need Advice


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Hey all,  I had a strange little event yesterday, and wanted to get everybody's take on what could be going on.

Yesterday I pulled my CTSW out to fly for the first time in about 5 days, and started it up as I normally do.  Choke was on, OAT was ~73°F.  The engine started right up, but once it was running the Alternator/Generator light did not go out as it normally does when starting.  It stayed lit at about half brightness and seemed to have a pulsing flicker to it.  I advanced the throttle to see if it went out, but it stayed lit up past 2500rpm.  all other indications were normal and the voltmeter read about 13.7v, normal for my airplane before turning on avionics. 

I normally don't like to do a shutdown until the engine warms to the 123°F takeoff temp, so I let it keep warming up.  It might be my imagination (or just the fact the engine was dead cold for 5 days) but it seemed to be running a bit rough.  after a couple of minutes, the Alt/Gen light went out, and the engine seemed to get smoother.  Once the temp hit takeoff temp I shut down, took off the top cowling, and inspected everything paying special attention to electrical components.  Grounds, battery, ignition module connections, voltage regulator connections, capacitor wires, plug wires, etc all looked fine, as did the carbs, balance tubes, and other components.

I re-cowled and restarted.  The engine caught on the first blade, the Alt/Gen light instantly went out, and the engine ran smoothly.  I went ahead and taxied out and had an uneventful mag checks at both 3000rpm and 4200rpm, and the flight went perfectly.

I never experienced this before with the Alt/Gen light, so I'm wondering about possible causes.  I'm not an electrician, but here are some ideas:

1) Voltage Regulator starting to fail?  (it's the original Ducati unit)

2) Capacitor starting to fail (assuming original, been on there since I bought the airplane)

3) I live in a humid climate...maybe some tiny spots of corrosion on the the stator that rubbed themselves off after a few minutes? 

Any other ideas or is the cause obvious to somebody on the forum?

Thanks!

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The connector block on the regulator rectifier is a plastic block, and the vibration does cause the terminals to wear into the block. Make sure they are all completely seated before you unplug the block to go any further to see if you can figure out where to focus attention.

At some point in the wiring, R, B, and C are all tied together, and are part of the positive circuit. The regulator rectifier case is grounded with a wire to your negative.

The light connects from L to C. Internally, L is part of the charging circuit, while C is the feedback circuit that regulates the output and eventually leads to the battery.

When everything is working, the voltage is almost equal so not enough power flows to light the bulb, but when the generator is not charging properly, power flows and the bulb lights up. So, make sure R, B, and C are all solidly connected, and that there are no loose wires in the black plastic block.

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Not sure about the engine not seeming smooth, but I recently had some issues with the regulator.  Similar to your explanation with it seemingly starting to work after a wiggle or reset.  Fought that on and off for about 6 months.  Eventually got to a point where the generator would not output, so had to really do some investigating.  Pulled the plastic connector to the regulator, and found that one of the yellow AC wires had a bad connection or was loose, apparently overheated, and melted the plastic to the point that it melted all over that AC spade connector, which just made the connection worse.  Replaced the spade connector and reattached well enough to get home.  Got home, decided to replace the regulator with a B&C AVC1, re-terminated all wires, and added a little dielectric grease.  Been rock solid ever since.

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i think you got your answer already but will add that yeah - possible loose wire or regulator is going.   Ive had mine fail within a 6 month period of having those same symptoms and ive also had, on a separate occasion, the connector burn up on me (arcing i think is what it was called) from a bad connection.         The biggest problem when this happened to me was losing the radio for comms.   Every since ive always had a fully charged portable radio in the aircraft.

 

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If heat over time is the culprit, other applications call for space between RR and mounting point to improve cooling. This is achieved with 4, quarter inch tall, hollow aluminum tubes to fit the mounting screws through. The standoff helps dissipate heat.

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3 minutes ago, airhound said:

If heat over time is the culprit, other applications call for space between RR and mounting point to improve cooling. This is achieved with 4, quarter inch tall, hollow aluminum tubes to fit the mounting screws through. The standoff helps dissipate heat.

The CTLSi is a different beast.

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There isn't much room in the nose of a CT for this stuff. Just about every answer I could think of to supply cooling to the regulator required some real compromises. Either requires composite work for a new scoop, installing a flapper valve, risking direct water exposure, or just simply mounting too far from the engine.

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It would not surprise me if my regulator is going.  It's the original unit from 2007 that has been flown through hot Georgia summers for nine years.  Hopefully it's just loose wires since that has happened before, but I'm sure if the wires have loosened and the contacts are arcing that is not going to do anything to help longevity of the RR.

The replacement I have for it is the John Deere unit a lot of folks have used (E-LSA).  I think I need to get a Y connector for two of the wires since the contact layout is a little different and two of the wires are combined into one on the Deere unit. 

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Andy,

Don't jump the gun and make more out of this than it is. It may have just been a poor connection which happens far more often that a VR failure especially in a CT. Give it some time and don't throw parts at it without more info.

VR failures in a Vans is totally different from a CT. Vans are their own worst enemy from their mounting choice that cause heat failures and now they did the same thing with the 912iS engine. Put the fuse box right behind the #4 exhaust pipe with no cooling. I fixed the cooling issue on 6 RV12's and they've never had an issue. Others on Van's website blame Ducatti, but failed the real cause and easy fix.

No mountain out of a mole hill.

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These are still solid state devices and the cooler, the better. The outside of the case might not get that hot, but the silicon junctions will be. The source of that heat is going to be little tiny cross-sections amounting to a few square mm.

I'm not saying we need to freak out and go through expensive retrofits, but it would still help to be able to get cool air blowing over the fins. Every 10c cuts lifespan of a silicon junction in half.

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5 hours ago, Anticept said:

These are still solid state devices and the cooler, the better. The outside of the case might not get that hot, but the silicon junctions will be. The source of that heat is going to be little tiny cross-sections amounting to a few square mm.

I'm not saying we need to freak out and go through expensive retrofits, but it would still help to be able to get cool air blowing over the fins. Every 10c cuts lifespan of a silicon junction in half.

Absolutely

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Corey,

As you may recall, Chanik explained this to us back in 2013:

Basically, his testing showed that the original Ducati regulator is a POS. It does a poor job of regulating voltage and is extremely inefficient, meaning provides less electrical power than it should while generating a great deal of internal heat, which reduces its MTBF (average life span).

The best solution is not additional external cooling, it is to replace the Ducati with a decent regulator. He recommended Silent Helix which has the additional advantage of regulating at 14 volts which allows it to fully charge a LiFePo battery.

Other properly designed regulators may also be available now.

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Hi Mike!

I have many of chanik's posts recorded, and I had expanded on some of his work before.

I 100% agree that the regulator is dogshit. It's an epoxy filled block which does not conduct heat very well.

The regulator in question is Silent Hektik. I have tried getting one imported and wanted to work with flight design on testing it and getting an MRA, but the manufacturer refuses to export the regulator outside of Germany, and also had got into a legal tangle with Rotax and want absolutely nothing to do with them as a result.*

* Rotax has a retracted bulletin from years ago that specifically called out Silent Hektik as one of the "unapproved parts" vendors, and said a few things in it that got them in deep, deep trouble. It was libel, plain and simple, and the issue was settled between their lawyers.

Anyways, as Chanik tested, Ducatti isn't the only bad regulator. He went though 3 or 4 regulators, all turning out to be trash and one being downright dangerous, before he found Silent Hektik. Good regulating circuits for permanent magnet generators take a bit of work to design and manufacture, and most regulators don't go through that level of effort. It's like opening and closing a valve for a fire hose, it's hell on the components. On the other hand, alternators are pretty low stress electrically, and last a long long time.

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