It's not down to coning forces.

Regards
Andrew

Hi Bart & Andrew,

Maybe I didn't word this properly or maybe I should have put it as to
separate postings. These are two separate questions. I didn't intend
them to be interrupted as part of the same question.

Seeing that the focus so far is on the noise question, and it seems
that it has to do with the blade colliding with the previous blades
vortexes from the posting responses so far. Is this something to
avoid? Does it cause harm to anything with the helicopter?