There is one I know of where a maintenance error lead to the tial rotor cables wareing through which resulted in the Tail Rotol Control going into a hard over position which resulted in the aircraft spinning out of control , which resulted with an impact into the sea, resulting in the deaths of all on board.
The S76 now has a spring assembly as a result which places the tail rotor in a setting that would allow a safe run on landing in the event of a cable failure.