Summary
The pilot reported that when he was about 3 NM from the departure point he smelt smoke, and then saw smoke entering the cabin and trailing behind the aircraft. He immediately turned back towards a suitable landing site about 1 NM away, but the engine lost oil pressure and performance started to deteriorate. The pilot carried out an autorotational landing with partial power into a confined area, and on touchdown the vertical stabiliser and tail rotor blades struck an anthill. Subsequent inspection revealed a ruptured oil line as the cause of the smoke and loss of oil pressure. Structural damage was confined to the tail rotor blades, horizontal and vertical stabilisers, tail rotor transmission and drive shaft, and tail boom.
