How to Prevent Dynamic Rollover
Dynamic rollover is the reason why take-offs in a helicopter must be undertaken with such care.
The pilot raises the collective very slowly until the helicopter is light on the skids, then positions the cyclic to ensure that take-off will be precisely vertical, before raising the collective further.
If at all possible, the pilot should ensure that both skids lift off at the same time, so that there is no pivot point to induce dynamic rollover. Students practise this extensively before going solo in a helicopter, since the take-off is one of the most difficult things they will have to do.
In addition, great care should be taken to ensure that one skid is not stuck in mud, in long grass, or on ice, since any of these can very easily induce dynamic rollover.
Dynamic rollover is particularly likely to happen when taking off from slightly sloping ground, as the helicopter is already at an angle. So sloping ground take-offs must be done very, very carefully. For this reason, they are considered to be one of the most difficult exercises in the PPL(H) syllabus, and one that can make instructors extremely nervous!
What to do About Dynamic Rollover
If you unfortunately encounter dynamic rollover, it is often already too late to start thinking about what you are going to do about it, as once started it is almost impossible to stop. The only way to guard against it is to plan for it during every take-off. Carefully check the skids in advance; are either of them stuck, or is anything preventing them from moving? If at any point the actual take-off looks like being anything other than textbook perfect, lower the collective smoothly but firmly, and get back on the ground and start again. There is no shame in being extra careful.
The saying that it is better to be down here wishing you were up there rather than vice-versa applies as much when “up there” is two feet as when it is 2000 feet. Do the take-off again carefully, and get it right this time. So enjoy your flying, but fly safely and don’t wreck any helicopters!
Decoding Science. One article at a time.