3 Top
I may be teaching your granny to suck eggs but...
Just double check the orientation of your vertical accelerometer , if it were 180 deg out i.e. upside down the phase angle you read will 180 degrees out and therefore give rise to the (at face value) strange discrepancy of de-tracking the rotor to achieve a lower vibe level.
It does depend on the values you are talking about but by and large3 bladed rotors such as on the 350/355 /120 etc have less tendency for abiguity than 4 , 5 and 6 bladers IE A large track spread normally DOES equate to large 1P vibes.
Whereas a 4 blader you can have a big 2 and 2 split with very low 1P and high 2P as per the 412 with its built in +20 -20 +20 -20 theoretical perfect track.
All these rules of thumb are of course out the window when you get an atypical blade in the pack
Have fun
Wunper
