David,

You should be able to isolate the problem to your charging system (alternator and voltage regulator) by turning off the alternator when the symptoms occur and noting whether they continue. If the symptoms continue after you turn off the alternator then it is not a problem with your charging system.

If you can narrow the search to your charging system, I would start with simple (cheap) solutions before replacing the alternator or regulator. My first suspect would be the alternator master switch. If the internal contacts on the switch are worn enough they can change the internal resistance thereby affecting the voltage going to the regulator.

Any ideas about what would cause my amperage to start fluctuating wildly about 5 minutes into a flight?

It starts out fine after takeoff at 15 amps and then goes to -50 amps for 30 seconds, and then gyrates between 5 amps and -50 amps for a minute and then goes back to normal. It repeats this sequence every 5 minutes.

My fuel gages also go down to zero during this episode and then back to normal.

Is my B&C LR3C Linear Regulator going bad?

(I'm getting these readings from my Grand Rapids EIS engine monitor. It's hooked up to a Grand Rapids EFIS Sport.)

Thanks for the help!

David T.
Legacy RG