And this is the point raised, almost every time, it always seems to drop (slowly) down from the hover height to the point of the rear wheels almost touching the deck again, then it’s up and away..... why does the chopper drop down before lift ? what is the transition at that point
I would suggest this may may be specific to the type of helicopter, or company procedures. It sounds as though it may be some sort of power/performance capability check. Ask one of the pilots, they would be only too happy to clarify for you.
It's not something we did on the type I flew (S-76C). Our procedure was hover at five feet, check N1 margin is >=3%, climb vertically to 25 feet with a rate of climb >200feet/min, rotate to maximum 15° nose down, accelerate to 60 knots, climb to 250 feet before commencing any turn, undercarriage up on reaching 60 knots, disarm floats approaching 75 knots. Job's done.
PS: Our tumble dryer door has a window.