I have done a lot of Dynamic Balancing on this installation, and find the rotor very sensitive to weight changes, and erratic phase angle behaviour often occurs during the process. I find that lifting into the hover, obviously applying torque to the transmission, will overcome the problems, but this doesn't comply with the mainteneance manual. Intend to seek a concession from Agusta to acquire Tail rotor balance data in flight, rather than at MPOG. Anybody got a view on the subject? Incidentally I have been using RTB Eqpt from Helitune, Chadwick Helmuth and Stewart Hughes,and yes I know there are a few aircraft which seem to be ok, but on the whole the A109's are very sensitive. I have a feeling this may be due to the design of the Tail section itself, but would like to hear other opinions.