This issue is noticeable for Helipads (for all helis) and was also raised in the developers forum by Hype Performance Group (their explanation and link below).
With Helipads, the Helo will “bounce up / to the side abruptly” when (or just before) landing. With many new addons for Helipads out now, I am looking to put this issue up for a vote to prioritize the fix given that it was acknowledged since earlier this year.
Excerpt from HPG…
“With the new SU11 helicopter flight model, operations on elevated platforms suffer from what appears to be a lack of a transition in handling ground effect. This effect seems to be worse for heavier helicopters. When approaching a platform horizontally, the helicopter will get a huge kick of energy exactly when the RADIO HEIGHT value rapidly decreases, as the center of the model crosses over the threshold of the elevated platform. This “kick” seems much worse for a heavier helicopter, and in ours it is also from the left (as opposed to simply rapidly rising upward).”