The pilot reported that on arrival over the landing area he noted there was a south-easterly wind of about 30 knots. He therefore planned to land into the south-east. He conducted a low pass in the planned landing direction at about 50 ft above the ground and observed there was no turbulence. He then made an approach at 80 knots with 20 deg of flap selected. At approximately 40 to 50 ft above the ground the aircraft encountered a high rate of sink Despite the application of full power and backstick the aircraft hit the ground heavily, dislodging the nose gear. It then slid for about 25 metres before turning over and coming to rest inverted.
The pilot said there was a hill to the south of the landing area, and he was aware this hill could cause turbulence when there was a southerly wind blowing. However, on this occasion he encountered very strong shear which he now believes is unpredictable in that he did not encounter it when he made the low pass prior to his landing approach.