Alternator Replace

[Cpt.tidy]

Just had my second alternator failure in less than 50 hrs. The first failure was caused by an oil leak that got into the stator. That was a legitimate failure. However; the second was just an outright failure. Sonex stators are very pricey. My guess is this is a generic part as most of the sonex parts are. Just looking for cross reference part number that will work. Any ideals.
Regards,
Jerry

[rizzz]

Just had my second alternator failure in less than 50 hrs. The first failure was caused by an oil leak that got into the stator. That was a legitimate failure. However; the second was just an outright failure. Sonex stators are very pricey. My guess is this is a generic part as most of the sonex parts are. Just looking for cross reference part number that will work. Any ideals.
Regards,
Jerry

Don’t quote me on this, I could be wrong, but I remember reading somewhere the alternator is a Kawasaki brand.
Might be worth searching though their catalogs and see what comes up that looks alike.

[Cpt.tidy]

Thanks, I’ll check it out.

[Dave Wolfe]

The voltage regulator appears to be a kawasaki part Im not sure if this is the right one:

21066 7011 voltage regulator

Also be warned aftermarket voltage regulators can cause issues. The aerovee stator resembles the jabiru stator, and jab stators fail with the B&C regulator designed for rotax engines. I believe the B&C is a "shunt" type. I dont recall anyone using the B&C with the aerovee and if it was successful or not.

[daleandee]

I would suggest that when & where you can you should support the factory. They have the correct, tested parts, that are exact replacements for your alternator & regulator. We need them to be here for a long time so give them your business when you need parts.

Dale
3.0 Corvair/Tailwheel

[gammaxy]

I'd be interested to learn more about this failure. Until your failure, the only failures I've been aware of has to do with screws backing out and cutting through the stator windings (addressed for quite a while with a Service Bulletin).

How did the oil leak damage the stator? I would have thought it would be pretty impervious to oil.

Also, the wire is relatively low voltage and if I remember correctly the coils are all cast inside resin, so it's hard for me to imagine how it can fail so quickly. I assume you measure an open circuit when probing the leads with a multimeter?

I'm suspicious there might be something else going on with the electrical system that's destroying the stator. Unless you are pretty convinced the oil leak caused your first failure, I'd be suspicious of another underlying issue like the voltage regulator and the rest of the electrical system. Is it possible there's some unintentional way to draw more than 20A through the alternator?

[Murray Parr]

I would suggest that when & where you can you should support the factory. They have the correct, tested parts, that are exact replacements for your alternator & regulator. We need them to be here for a long time so give them your business when you need parts.

Dale
3.0 Corvair/Tailwheel

I totally agree with this statement. Sonex has very good after market service and I would love to see that continue. Support them where you can especially if you don't have the freight issues of shipping to Australia or other far away lands.

[Cpt.tidy]

Thanks for the great input. After further testing i have determined that is in fact a regulator failure. All of this was preceded by an engine failure at 276.0 hour requiring a forced landing. All turned out well. However I was surprised the engine failed with such a low numbers of hours of usage.

The number four cylinder valve broke in the middle, damaged the head, went thru the piston, and punched a hole thru the case. I've since rebuilt the engine and that was when i encountered the charging problem. But, I think I have that solved.

I am however disappointed that the engine failed with such a low number of total hours. I am a licenced FAA mechanic and maintained the aircraft to the highest standards. This has created a trust issue with the aerovee engine.

As to first stator failure, oil seeped into the stator assembly causing it to short out. You could definitely smell it and see the results on the instruments.

Thanks for all the input.

CPT Tidy