Some time back I had problems with my Hartzell prop made of actual 84 inch diameter cut down to the 70 inch diameter with no taper to the blade (thick tips).  I had vibration at various rpms.  Well, unfortunately I have changed two things and the odd vibrations are gone.

 

1.  I found the forward bulkhead for my aluminum spinner was not quite round and "fill" tape had gathered on the slight gap side.  So, after creating a new mounting flange for the lathe and cutting a new bulkhead out of nylon to the exact required roundness, size and taper, this new firmer bulkhead was installed.

 

2. In the spirit of Appendix D and while the spinner was off, I thought I would lubricate the hub as recommended by the Hartzell prop maintenance manual - especially since I had 150 hours on the prop (probably the longest any hub had not been serviced for blade replacement).  Surprisingly, both hubs took an enormous amount of Aeroshell #6 grease (40 strokes) to finally eject some old grease.  So, I was flying without enough greasy kid stuff.

 

Anyway, the funny vibrations are gone.

 

PS: This post was repeated on the Lancair Forum Site:

 

http://www.lancair-builders.com/forum/index.php?s=

 

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