The problem is something to do with the collective trim when in/near the fully down position, I'm sure someone will be able to explain in more detail. A/C starts to basically bounce up and down, and obviously the first time it happened it caused a few hearts to beat a bit faster..... Saw pilots giving it a shot the other day and thought the thing was gonna hit it's tail off the ground! I'm told by one of the pilots that the situation can be avoided if known about, and Eurocopter are looking at a fix.