Electrical help on PA32....

[SIIHP]

I have an issue that has three mechanics stumped... Alternator light came on and voltage started to slowly drop in a turbulent flight, no alt field circuit breaker pop. Prior to the sudden light and slow drop to 25.8 or so, the voltage was a very consistent 27.3v on engine monitor leading mechanics to tell me it is not likely the regulator. Recycling Alternator didn't help extinguish the alternator light. Safe landing after shutting down electrical gear, and mechanic promptly pulled alternator which had good belt and connections to test on bench, and it tests fine. Battery tested fine and 27v. Alternator is getting 27v at the field wire, but the other wires to the alternator only 8amps. He checked under the nose baggage near gear pump and the rectifier and heat sink there, (Part circled in photo) and it has 27v in, and 8v output there. One shop said that's normal, and its job is to prevent back flow. Two said not enough voltage there to get the alternator to output...they are questioning if should change the rectifiers (part 681-007) but another mechanic doesn't believe this is the issue, as the alternator is getting 27v, that the drop from 27v to 8 is normal to prevent the back flow. Any electrical system gurus on board? Thanks in advance!

 

[Rzitren]

 

[SIIHP]

 

[Ray93J]

 

[SIIHP]

 

[Ray93J]

 

[SIIHP]

 

[Ray93J]

 

[SIIHP]

 

[Ray93J]