I purchased my Turbo Twinky a few years ago and it had been upgraded with Kelly Aerospace Alternators in 1999. I recently had the aircraft in the shop and was informed only 1 alternator was putting out. The alternators had been overhauled in 2008 during engine OH. A new alternator was swapped last week with the inop one and it does not work either. The shop believes it is a wiring problem but we cannot seem to locate a wiring diagram. The wiring was tested from the alternator switch to the field connection and the voltage shoould read the battery voltage with the switch on however it does not. I have not been able to locate the STC in all of my paperwork although a mechanic made a logbook entry in 1999 indicating the generators were removed and replaced with alternators. Has there been more than 1 STC in recent years for these conversions? After reading posts from previous members I am wondering if it might be time to upgrade both alternators to something better such as Plane Power Alternators for reliability and weight savings? Any insight would be appreciated. Jeff

I installed the Plane Power system recently. I am very pleased with it. I gained about 20 lbs of useful load and replaced it with a simple system that provided alternator warning lights

I know that this is old but thought if anyone is interested, I did the same as Kristin. I unfortunately bought the Kelly alternators from a mechanic at my field and was sold an incomplete STC. I managed to get the STC from Kelly, who I might add was very helpful, but the regulators were the wrong ones for the STC. I eventually bought the right ones through Aircraft Spruce which took nearly a year to get as Kelly had to make them up specially for their alternator according to their STC. Very frustrating! Here I am after all that, I decided to go and buy the complete kit (which I should have done originally) from Plane power and as a result, they are installed and working great. I have a pair of Kelly alternators with the correct regulators and other accessories for sale if anyone is interested. I also have a perfectly good pair of generators and regulators for sale.
Jim

If your plane is upgraded to alternators, the Plane Power troubleshooting flowchart is an excellent resource. Even if you don't have their system installed it should serve as a baseline starting point and save you quite a bit of time.

http://www.plane-power.com/images/troub ... ternal.pdf

We just finished this upgrade on our PA-30 and love it.

Tim