My first tail-rotor failure was actually a self-induced tail-rotor drive-shaft failure. The drive-shaft jumped out and flailed because the first hangar-bearing behind the jet exhaust (in an Iroquois) got overheated and failed due to a lubrication break-down. The reason the lubrication broke down was because I'd been hovering downwind winching trainee crewmen up and down for over 30 minutes. Not a significant downwind component either -just about 4 or 5kts. However it was sufficient to pool the hot exhaust gases around the No 1 hangar bearing and cause it to seize and jump out.
Of course you could always criticise anyone for hovering out of wind however given that the target was a rock in the middle of a creek and that the only hover reference was out of wind, it seemed a reasonable idea at the time. But full marks to the crewman instructor who cut the cable and dropped the two guys in the creek before we landed on the bank (luckily without spreading the skids). Naturally I got criticised, but up until that time nobody had ever mentioned that particular vulnerability of the tail-rotor drive-shaft. No doubt others have managed to do the same trick since - and others yet unborne will repeat it. It was interesting that I had a buzz of about 30 sec duration (only) through the T/R pedals before it broke lose with a loud bang.