Drop by this place because not sure which part of my car is making random aeroplane  noise, they removed alternator from my car spin it,  told me bearing is good therefore its not the culprit probably Ac compressor, then they removed the back plastic cap, show me carbon is worn, OK change it then air blow the whole alternator, pasang back then start car, done, I asked for bill my expectation is more than 50 less than 100 cos carbon only cost a few bucks to my surprise the uncle charged me 120, 10min job, don't require dismantle whole alternator+ few dollar parts for 120 🤔