balancing act

Here's one for the pros: I was balancing my tail rotor and had it down to
0.27 ips and still had just a touch too much weight where I had added it.
So still needing to safety wire a bolt that is located in the center of the
tail rotor output shaft, I chose to safety it to a hole 180 degrees from the
weight. The safety wire was small, 0.025, so I didn't expect to see the ips
go to zero, but I hoped they would decrease maybe to 0.20. Well it didn't.
All of a sudden I had 0.9ips, so I shut down and removed the wire and ran
again. This time I got 0.5 ips. The balancer reading did not even come
close to repeating. The phase angle was also different. In an experiment,
I would run up from idle to full chat and take 4 averaged readings, come
back to idle and go up to full chat again for another 4 readings. Never
repeats. Can't find anything loose in the drive or on the blades. If I
pull a set of readings at 2500, 2600 and 2700, all the readings pretty much
agree with the exception of ips increasing a bit with rpm. However if I
take it to idle and come back up, I get a different set.
Any ideas?
--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell