On August 3, 1997, at 1930 central daylight time (cdt), a Beech A36, N4640M, operated by a commercial pilot collided with a steel post while taxiing after having landed at the Spirit of St. Louis Airport, Chesterfield, Missouri. The 14 CFR Part 91 flight was operating in visual meteorological conditions without a flight plan. The airplane received substantial damage to the left wing. The pilot and five passengers were not injured. The flight originated from Osage Beach, Missouri, at 1830 cdt. The pilot was taxiing on a private taxiway when the left wing contacted a 6 inch diameter steel fence post which had recently been erected. The portion of the wing which contacted the post was about 4 feet inboard of the left wingtip. The fence post had been installed as part of a gate to enclose a private hangar area. The fence post was located adjacent to the pavement as was another post on the other side of the taxiway. The clearance between the posts was 38 feet 5 inches. The wing span of N4640M was 33 feet 6 inches. The pilot reported that the posts had been installed sometime after he had departed the airport on the previous day. He also stated that he was taxing into the setting sun which hindered his vision.