Back in the early '90's, a PPL instructor of mine at the time (an RAF heavy jet man) was killed in a dreadful accident at Oxford, after the PA28 he was instructing in encountered the wake turbulence from a departing S61 whilst on short final - it was British F1 GP day at Silverstone.
As a PPL u/t at the time it hit me hard and always made me very wary of heli-induced turb, especially as the place where I did a lot of my subsequent flying was at Blackbushe (intensive heli-ops, everything up to S92 size these days)....be careful out there!