Alternator issue

[S2D]

Running a plane power (Hartzell) alternator.
Charges fine below 1200 rpm .
Cuts out above that.

Any ideas why?

 

[Mr. Ed]

I had one that behaved similarly. Mechanic said it was the voltage regulator. Paid to have it overnighted and installed. Same problem. Bought a new alternator and had it flown in. When I got home I took the faulty alternator to a shop that checked it out and said the brushes were bad. Yup, $5 parts fixed the problem. Try that first.

 

[Ken Robbins]

I've had a few do that, usually was brushes but others had a loose aft bearing. A light cleaning of the slip rings with fine Scotch-Brite seems to make new brushes happy on the Hartzel Alt's. The loose aft bearing isn't always as obvious as it would seem, you need to get good look at the end of the shaft to see the play.

 

[S2D]

Thanks for the info.
Ill look into it.

Are parts readily available for those alternators.

 

[Mr. Ed]

Not me, of course, but I know an owner that takes their alternators to a shop that typically repairs ground based vehicular alternators. They seem to have no trouble procuring parts at reasonable prices.