About six months ago we installed a new three blade MT prop. Soon after, we started to hear a faint squealing noise that sounded like a loose alternator belt. Upon further investigation it turned out that our alternator pulley was touching the cowling. I think the slightly heavier prop might have exacerbated the situation. We pulled the prop, again and installed a shorter alternator belt. Performed test run up and still had the squeaking at idle and when taxiing.
We figured that we had a bad alternator bearing and replaced the alternator. Performed test run and still had squeaking.
At this point we notice that if you bring the idle up to about 1100 RPMs the squeaking goes down but now we have enough oil pressure to cycle the prop which made the squeaking almost go away.
Called MT prop who were incredibly helpful as usual. When I told him what was going on they replied with. "Oh, yes those blades whistle at idle".
So although it had nothing to do with the alternator at least now I don't have a hole in my cowling from the alternator pulley. And we have a new alternator.
I wanted to post this as I haven't seen anything anywhere about composite prop blades whistling.
dan
We figured that we had a bad alternator bearing and replaced the alternator. Performed test run and still had squeaking.
At this point we notice that if you bring the idle up to about 1100 RPMs the squeaking goes down but now we have enough oil pressure to cycle the prop which made the squeaking almost go away.
Called MT prop who were incredibly helpful as usual. When I told him what was going on they replied with. "Oh, yes those blades whistle at idle".
So although it had nothing to do with the alternator at least now I don't have a hole in my cowling from the alternator pulley. And we have a new alternator.
I wanted to post this as I haven't seen anything anywhere about composite prop blades whistling.
dan