On February 27, 1996, at 0830 Pacific standard time, a Cessna 180A, N9669B, registered to and operated by the pilot as a 14 CFR 91 personal flight, collided with an open manhole while taxiing to the fuel island at the Hillsboro Airport, Hillsboro, Oregon. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the private pilot, the sole occupant, was not injured. The flight originated from Independence, Oregon, about one half hour before the accident. The pilot reported that after landing he was taxiing to the fuel island when the left main landing gear rolled into an open manhole near the fuel island. The left wing contacted the surface, substantially damaging the wing and aileron. Earlier in the morning, a work crew had removed the manhole cover, but did not place the orange warning cones around the area.