Alternator Ghost

[210TC]

Sorry to hear the news.
I suspect you now have a factory schematic and all has been verified.
If not, I recommend you look for a mechanic that does not want to touch the system until he has one in his hands. If you do not know of one in your area look elsewhere.
The only thing left to replace is the airplane.

[Green Hornet]

Norm,
That is to say the least frustrating! Was the instrument panel ever removed ?
I once had a short that could not be found and it turned out to be that the mechanic took off the instrument panel and replaced one of the screws with a long screw that caused a short. I know I am grasping at straws but I thought at this point to pass on an experience. Like David I am sorry to hear after all your part swapping and analysis the issue is still not resolved.
Good Luck

[Norm]

Yes, we have a full schematic of the charging system -- it's amazing what mechanics can pull right off of their computers on the internet. They didn't start working on it until they printed it out.

The plane is a 2002 and doesn't have any history of panel work being done. It has the original factory IFR package and instruments.

It was annualed just before I bought it so I wondered if something could have happened then. But I can't imagine what could have been done during an annual that would have caused this. The annual was very straight forward with no issues.

? ? ?

[Wayne]

Maybe sojorrn is on to something their. Try taking the plane up and leaving the avionics master off and see what happens.
If the plane seems ok then pop all the fuses out. Then turn the avionics master back on and watch what happens then. from their start pushing the fuses back on one by one.

Just a thought.

[Norm]

Maybe sojorrn is on to something there. Try taking the plane up and leaving the avionics master off and see what happens.
If the plane seems ok then pop all the fuses out. Then turn the avionics master back on and watch what happens then. from their start pushing the fuses back on one by one.

Just a thought.

That's a good idea and I have turned the avionics master off and it still acts up. I, unfortunately, do not have the circuit breakers than I can pull "off" -- just the factory ones that you can reset if they pop out. But in this whole process there has never been a circuit breaker pop out. Avionics master ON or OFF, high electrical load or no load, it doesn't seem to make any difference.

We have learned that B&C doesn't make a 70 amp alternator so we're looking into a Plane Power 70 amp alternator & regulator. BTW, it seems like 70 amps with a 24 v system is more juice than anyone could use ...... I can see that much amperage with 12 volts, but 24?!?

Thanks for your ideas and suggestions, guys.

[aero101]

I once had a customer with the lamar alternator that drove me nuts, same kind of intermittant problem. I had pulled alternator and had bench checked twice, checked good both times, and finally found that under load the brushes were not making good contact. ($5.00 FIX) Would highly recommend you have system completely checked with a MEGGER... by this I mean aircraft ground system from engine to airframe to panel, each individual wire from connector to connector, and resistance values in alternator system itself being careful to not induce megger voltages into components like the regulator. (disconnect wires and ring out connector to connector) If you still can't find fault, I think I would scrap the Lamar system, and install newer lightweight system with all new wiring? At this point I'm sure you've got enough time / cash tied up that this would have been the less expensive alternative to start with? Wish you luck as have so many others in finding those stray electrons!!!

[Wayne]

I don't know nothing about the 24volt system. But, I think I remember someting about their being some kind of box under one of the front seats that has to do with that system also. I'm not sure though.

[Norm]

I once had a customer with the lamar alternator that drove me nuts, same kind of intermittant problem. I had pulled alternator and had bench checked twice, checked good both times, and finally found that under load the brushes were not making good contact. ($5.00 FIX) Would highly recommend you have system completely checked with a MEGGER... by this I mean aircraft ground system from engine to airframe to panel, each individual wire from connector to connector, and resistance values in alternator system itself being careful to not induce megger voltages into components like the regulator. (disconnect wires and ring out connector to connector) If you still can't find fault, I think I would scrap the Lamar system, and install newer lightweight system with all new wiring? At this point I'm sure you've got enough time / cash tied up that this would have been the less expensive alternative to start with? Wish you luck as have so many others in finding those stray electrons!!!

Great suggestions, Jim. We've checked out the relevant wires with a meggar and checked resistance of all wires, connections and cleaned up the grounds. We've also tinkered with the brushes. You're so right about having to disconnect the wires as the meggar introduces some pretty high voltage.

We're going to start replacing the *ENTIRE * charging system, piece by piece starting with a field approval for a different brand alternator and regulator from the original. If that doesn't do it then I'm selling the airplane for parts.

[aero101]

Sure you're probably pulling out all your hair by now and looks like you have done about all can be done... The sad part is it's probably another $5 fix, and sometimes the challenge of finding those problems just isn't worth the agravation and cost. This one I got into, I probably had 40hrs into, had replaced most components except alternator and then discover bad brushes? No way I could charge customer what I had in it, just wrote off as education!!! Good luck on new installation, if you decide you're going to part it out, let me know....

[Norm]

Problem solved! Well.....99%.

Since my last post we've:

1. Run an additional ground from the engine to the firewall
2. Installed a Plane Power 70A 28V alternator and Plane Power regulator.

I've flown the plane for about 7 hours since the new Plane Power was installed and the alternator has not gone offline. However, the little red warning light comes on and goes off every few minutes for no logical reason at all (cold, hot, load, no load, idle, cruise) ... but the alternator keeps charging according to the little ammeter on the right side of the panel and the Garmin 496 reads a steady voltage ~ 27.5V. I can deal with the red light with a piece of tape. Maybe I'll address that issue later ......... much later.

BTW, the Spokane FSDO guy we worked with was great. He approved the install quickly and offered helpful suggestions. He said that if the new charging system doesn't work then try running an 18 gauge wire from the engine ground to the negative battery ground in the tail thus bypassing the frame. The theory is that we can reliably test the resistance in wires but the frame is a less reliable resistance conductor. By pure coincidence I was talking to a helicpoter pilot the same day who had a similar problem and suggested the very same thing.

WAs it the extra ground wire or the Prestolite/Kelly Aerospace alternator & Lamar regulator combination? Not really sure, but in our conversations with various techs & engineers most everyone agreed the Kelly alternators have the weakest reputation among alternators. The Plane Power weighs 1.5 lbs less and puts out more amps @ lower RPMs.

Finally, after 7 months of dealing with this I can finally trust my charging system enough to plan a trip out of town.

Thanks, guys, for all your input and suggestions.

[Green Hornet]

Norm,
That is good news That intermittent light would drive me nuts but it sounds like you have the situation under control enough to tape it for the time being. There must be a loose connection somewhere?? I had my ignition switch go dead bug but my sweet heart got me home and then died. I replaced it and she roared to life . Now if we can get the weather to cooperate and the fires to take a break we could actually go somewhere. Congrats!!!!