N30WH

The pilot reported to the National Transportation Safety Board investigator that he had departed Exeter Airport, California, at 1142, and flew down to Porterville Municipal Airport to practice landings. He entered the landing pattern at Porterville and made two landing approaches, both of which he terminated in a go-around. On his third approach he made a poor landing and attempted a go-around. He applied full power, the airplane veered left, and upon contact with ploughed furrows adjacent to the runway the airplane nosed over. The pilot stated that the airplane and engine had no mechanical failures or malfunctions.