The pilot was conducting cattle spotting operations, operating from an area of flood plain on the property. After takeoff on the accident flight, a right turn was commenced when the aircraft reached about 250 feet above ground level. At the completion of the turn the nose dropped but the pilot was not initially concerned due to the prevailing turbulence. He soon found that he could not raise the nose by use of elevator control. Witnesses saw the aircraft commence to dive, and the attitude of the aircraft change until it was inverted. It remained in this attitude until ground impact. On this aircraft type, the horizontal stabiliser is attached to the fuselage beam by two 5/16 inch diameter rose joints mounted vertically. The all-flying stabiliser is operated by a push-pull rod from the control column. One of the rose joints apparently failed during the flight, causing the pilot to lose control of the horizontal stabiliser.