over-voltage

[stackj]

Ed...

YOU are the same age as my Skymaster. I wish I was in that age group!

[edasmus]

Thanks Jim....Yes, it is kinda funny that me and my airplane are nearly the same age. In April of 2009 I had the opportunity to fly my Skymaster down to Springfield, MO to meet the first owner back in the early 1970's. I actually met him through this website. Anyway, his name is Paul and he is a super nice man. He gave me photo copies of his logbook that noted the hours that he flew the airplane, as well as the original invoice that showed all the options the plane had when it was new, and lastly a photo of the airplane when it was new. It was very cool and the fact that I was in the 1st grade at the time makes it even more special. I can clearly remember being in the 1st grade.

As for my electrical issues, I just returned home after flying with my IA and fortunately the electrical system misbehaved immediately upon gear retraction on take-off. He had his volt meter attached to the buss to monitor exactly what was happening. One thing that was clear before we even departed is that the alternators are set too high. They are making 30.5 to 31 volts and I guess it should be more like 28 to 28.5 volts. The fact that the voltage is so high leaves very little margin to the 32 volt limit for the over-voltage sensor during normal voltage fluctuations. He also suspects something is up with the alternator field circuit breakers but at this point I am not exactly sure what it all means. He feels the system is enough out of spec that after making some adjustments he wants me to fly some more and see how it goes. He cannot rule out arcing somewhere in the system similar to what caused the beginning of this thread but after searching the last 4 days and finding nothing he is going to make these adjustments and we will see what happens. Stay tuned.

Ed

[stackj]

Circuit breakers can surely be a problem. When I first got our Skymaster (17 years ago) we had problems with the main alternator bus breakers blowing. Everything would run fine for a while, then one of the mains would blow. Shortly after that, the other one would pop. There was just no way you could keep the alternators on line.

I finally purchased two new main breakers (35 amp as I recall), replaced the originals and the problem went away. Since that time, I have upgraded the alternators to the 60 amp units (The original were 38 amp) and, of course, have upgraded the wiring, breakers, etc. to support the higher current capability.

I gues the object of this reply (if there is one) is let you know that circuit breakers can weaken with age. The breakers are not that expensive and could save you some trouble. It does seem that you and your mechanic have most likely identified the real culprit with your voltage checks. I would expect that adjustment of those would eliminate the issue if you are simply having the electrical system shut down. The overvoltage system should not blow the field breaker when it activates. If the breaker is popping, I would suggest that you do both the regulator adjustments and replace the field breaker.

Good Luck and Blue Skies!