Thanks for your inputs ya'll!
I've been traveling and very busy on some other things and still hadn't had the chance to come back here to pprune to check out for possibles replies to my still ongoing issue.
BJC, the Tarsyns have not been replaced for a while in this helicopter and they have been interchanged in the helo just to troubleshoot the issue but it keeps doing it. I will check it again just to make sure, though. Thank you.
Torquelimited, yes it indeed is a BH412HP. We also do have a 4-axis 412EP which, by the way, has never had this problem. BTW, this is a recent issue as it hadn't happened before to the a/c. Thanks, though.
Mr. Shawn, No there is no turn while passing this speed. It's been doing it only on this one helicopter for a couple of months now.
JetA1Pilot, No we have not monitored the API's nor I know if they are flying SAS or ATT. ATT mode I believe it is but I'm not sure. Will check and let you guys know.
Helix, the CMT's were already checked and the one for the yaw channel was faulty (shorted) leading us to think the issue would be solved but it wasn't. It's keeps happening.
Again thank you very much for your inputs. Will try your advises and let ya'll know.
Regards,
CL.