I can recall two from the UK's AAIB reports over the years, but can't find the actual reports after a quick search through the bulletins - if my memory is incorrect, pease correct me
One a Westland Scout where the pilot noticed a rearwards cyclic restriction, assumed hydraulic failure, ended up in a diver training lake, occupants wet but otherwise unharmed. Turned out it was a map in the passenger's lap causing the restriction.
Two - a Gazelle with the front pax seat straps not properly secured, the substantial buckle fell forward, restricting aft cyclic in the hover. Crashed, no injuries IIRC.