Hartzelll 3 blade prop

Anyone here converted an Arrow 180 to a three-blade prop? My flying
club recently converted its Arrow when the two-blade prop was found to
be shot during its overhaul. The three-blade was cheaper than a
two-blade, which seems odd to me still, so that was the choice. The
problem is that it vibrates a lot, especially at lower RPM (below 2200).
I joined the club just after the replacement so I don't know what the
two-blade was like, but it now vibrates a lot more than my Skylane did
(I realize the 6 vs 4 cylinder engine likely makes some difference
here). However, other club members say it vibrates a lot more. We were
told that the prop could be mounted in one of two possible positions,
180 apart and that there was no way to know in advance which position
was correct (this also seems odd to me). After the first test flight,
the prop was remounted and the vibration was less, but still seems
excessive.

I'm just curious if others have noticed this. I would have thought the
three-blade would have been smoother if anything, but that certainly
isn't the case. We're considering taking the plane to a shop that can
do a prop balance, but the engine is near overhaul so we're considering
waiting until next winter when we'll get both done.


Matt