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I love electrical issues.....(kidding)
I have had similar issues although not having anything to do with the cowl flaps. Herb, you need to ask more questions. You say the alternators drop off line. Is the over-voltage sensor tripping the alternators off? In other words, is the over voltage annunciator illuminated after the event? It sounds like it is because as you say, turning the master switch off then on resets the over voltage sensor.
I do know that I cannot solve this problem but I can tell you what my IA uncovered when I had this problem. The first thing he checked was the voltage across the entire system. We went flying to do this and he had me running all sorts of appliances. The gear went up and down many many times. The voltage should be darn close to 28.4 if my memory serves. Please verify this. Apparently the voltage regulators can wander and should periodically be checked to make sure they are keeping the voltage at the proper value. My voltage had crept up to near 31 volts which is way too high. The over voltage protection should trip the alternators off line about 32 volts (again please verify). As you can see, any momentary spike in voltage such as operating the power pack for the gear, or maybe even the cowl flap motor for all I know, can exceed the parameter for the over voltage protection therefor tripping off the alternators. Once the regulators were "dialed down" a bit to get the voltage correct, the problem went away.
In addition to accomplishing this task, my IA replaced my master and alternator switches as they showed signs of arcing. He also installed a diode somewhere in the landing gear system to dampen the inevitable voltage spike that occurs when the landing gear power pack is called upon or I believe more accurately, when stopped being called upon. In fact, I could hear a "pop" in my headset when the power pack stopped. After this corrective action, I have had no further issues or popping in the headset and it has been about 100 or more hours now.
As I write this, my IA is installing a digital buss voltage readout in my panel. I want to know exactly what the voltage across the buss is at all times. I hope to be able to see when the regulators need an adjustment before they get too far out of whack as well as knowing that the battery is getting charged at the proper voltage so as to not induce any boiling or insufficient charging.
These issues are never fun. I would suggest finding a tech who is extremely proficient in electrical issues on the SkyMaster. It will be worth the savings in grief alone. In the meantime, be as precise as you possibly can in describing the symptoms.
Good Luck,
Ed
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