On September 16, 2002, at 1810 central daylight time, an amateur-built Bailey DSA-1, N304MB, owned and piloted by a private pilot, was substantially damaged during a precautionary landing after an oil line failure during flight. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The pilot was seriously injured. The local flight originated at 1800. In a writtten statement the pilot said that the plastic oil line from the engine to the oil pressure gauge failed. He said that thick smoke and oil were present and he elected to land the airplane before a fire could start. He said that there were only corn fields and he stalled the airplane about 10 feet above the ground during the precautionary landing. He stated that the airplane hit the ground and the shoulder harness attachment broke loose. The pilot/owner reported that the most recent annual condition inspection was performed on July 5, 1998.