On February 25, 1995, about 1029 eastern standard time, a Grumman AA-5B, N28815, collided with the ground during a forced landing near Salisbury, North Carolina. The airplane was operated under the provisions of 14 CFR Part 91, and visual flight rules. A flight plan was not filed for the personal flight. There were no injuries to the private pilot nor his two passengers, and the airplane was substantially damaged. Origination of the flight was Gold Hill, North Carolina, about 1020 on the same day. Shortly after take-off, the pilot reported that he detected a burning odor, and noted that the engine oil pressure was at zero. The pilot attempted to make it to Salisbury Airport, however, the engine began to vibrate and subsequently seized. A forced landing was made in an empty field. Upon landing the nose wheel collapsed. The pilot also reported that, as the airplane was being moved, a loose oil line was found. The line had been replaced during the last annual inspection in September 1994. The aircraft had been flown approximately 14 hours since the oil line had been changed. The pilot reported that during pre-flight examination of the aircraft, no oil was found in the engine compartment or on the ground. Upon examination of the aircraft, oil was found all over the belly of the aircraft. Additional inspection revealed that the oil line from the bottom of the oil cooler to the engine had separated from the fitting at the engine. The last couple of threads on the fitting appeared to be shiny. The fitting was removed and examined for possible cross threading. The threads were normal and contained no evidence of being cross threaded. The hose nut also contained shiny threads, and the last thread was pulled out of the nut. The inspector reported that the hose nut had come loose and the engine vibration caused it to wear against the fitting until the oil pressure forced the hose off and pulled the last thread with it.