Circumstances:
The pilot was undergoing a ninety-day flight check. On the downwind leg of the second circuit when the landing gear was selected down, the nose gear extended and locked but both main gear legs remained retracted. Attempts to manually pump the main gear down were unsuccessful and the nose gear could not be retracted. The instructor landed the aircraft on the grass with the nose gear extended and the main gear retracted. Subsequent investigation revealed the aircraft hydraulic system had suffered a total fluid loss. The loss occurred from a hole in a hydraulic down line caused by abrasion from a rudder cable fork end.
