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This is to any of you Jabiru 3300 (120 HP) engine flyers out there.
I had a new battery that was only 1 year old dye on me in flight, I replaced it with a new battery and in flight my Volt meter is not showing it over 12V? Is there any quick tests for me to do to make sure that its not my Alternator that's at fault?
Comments Please on any quick Alternator tests for me to make sure?
The quality of the Stator (which is connected to the flywheel) is prone to failure. They are hand-wound and will sometimes rub. I have had to replace mine twice. See the attached pic for a fried one. I've had mine fail in flight once and I could smell the burning varnish.
When the stator fails, the battery will not charge. The quick test is to disconnect the terminal leads to the Stator and measure the resistance. I cant remember the difference in resistance between a good one and a bad one, so I recommend calling Arion Aircraft (who are now supporting Jabiru) for that information.
Thanks for your response, Wow that Stator in your picture looks messy, Is it normal for the Stator to fail that regular? you mentioned it has happened to you twice (How many Flight hours is that between replacements?) does the whole Stator have to be replaced or just the effected Coils that are worn?
I also took your advice and have sent an email to Arion Aircraft for their input on this issue of a failing Stator.
When you have a moments please fill me in on my extra questions above
I follow the Jabiru Engine Forum on Yahoo and there has been the occasional report of a stator failure, but I didn't get the impression it was a frequent or common problem. Hopefully, your's is good. I have seen reports of some people re-winding the stator themselves or getting it done at a shop that rebuilds automobile alternators and starters. (Some shops won't touch it if you mention "airplane," tell them it's for your airboat! Ha!) There's actually a Jabiru factory-approved mod to rewire the stator so that it produces charging current at idle - probably worth doing if you have to get the stator rewound.
More common failures are the connections between the alternator's AC output and the voltage regulator or the voltage regulator itself. Personally, in 590+ hours on my Jab 3300, I had the AC wire connectors start to fry (but didn't fail) and replaced them with soldered connections. My original voltage regulator did not fail, but I noted a hot spot on the back of the regulator where the epoxy was melting, so I proactively replaced the regulator with a genuine Kubota-brand regulator. (The original regulator is a copy of a Kubota regulator.)
It's good that you mentioned that you checked charging current in-flight, since the Jab's alternator doesn't produce a charging current at idle - it usually kicks-in at about 1900 rpm+.
I've never had a regulator failure in 285 hours, but I do keep a spare on hand because I heard they could be an issue.
I get enough current for charging at 1400 rpm+. I wonder why yours needs so much more RPM?
I don't know if Jab publishes a spec, but what I've always seen on forums, etc., is that the engine typically produces charging current "at about 1800-1900 rpm." It really doesn't matter, as it's a rare situation that the engine would be operated in the 1400-1900 range for any length of time so as to allow depletion of the battery. Typically, one is only within that reduced rpm range for a brief period during take-off and perhaps a few minutes at best on a long, slow descent - it's certainly never been an issue for me.
Thanks for your input, I run at 3000 rpm on take-off then back to 2600 rpm for normal cruise.
The first failure was shortly after my first engine run. Jabiru replaced it for free because it was basically faulty to begin with.
The second stator lasted less than 80 hours. I had to pay for that one.
The one I have now looks to be much better quality and has lasted over 200 hours. Hopefully they have improved their process.
You cannot replace one coil. The whole thing is basically one wire wrapped around multiple coils.
Out of curiosity, Mike, what's the serial number of your engine?
What about yours?
Mine's 33A 2427 - it was built in the transition from the "2nd generation" engine to the "3rd generation" engine - so it's a "late hydraulic" engine but with external oil lines deleted and replaced with fully internal oil circulation with hollow push rods, bigger cooling fins, and bigger crank bolts and through-bolts. However, it does not have the pistons with recesses to prevent hitting a stuck valve or the roller cam that the fully-3rd gen engines have.
So Mike, if they have to replace the Stator, do they replace the whole thing (Stator), or do they just replace the coil on the Stator and return it?