Probably not relevant but I seem to remember from my years ago on 206s, that it is possible to fit the main gearbox support links the wrong way round, as they are handed, and this can affect the handling when collective is pulled. It is however a memory from way back.
We also had a pilot who complained that the aircraft took off as he rolled the throttle up, so one of our engineers went out and took the collective clamp off and put the lever down.