I never had a particularly good feeling when hearing slicks (Hueys) especially the old 2 blade rotors. Of course, I was never a grunt wanting out of a bad place & waiting for that sound to help me.
I rode them. We had them working our firebases to help repel Charlies. Had gunships overhead late at night with miniguns plowing the banana scrubs around us. They’ve helped us by quelling mortar fire when we were required to fire support for somebody in trouble. Got lots of reason to thank them and I do.
When I got home and heard slicks my chest just kinda shrank-up inside. The only reason I can think of is that I associate that whump-whump with something bad happening.