On April 8, 2005, about 1830 central daylight time, a Cessna 152 single-engine airplane, N68472, sustained substantial damage while landing at the Stillwater Regional Airport (SWO), near Stillwater, Oklahoma. The student pilot, sole occupant of the airplane, was not injured. The airplane was owned by Christiansen Aviation, Inc., of Wilmington, Delaware, and operated by Oklahoma State University, of Stillwater, Oklahoma. Visual meteorological conditions prevailed and a flight plan was not filed for the solo instructional flight. The local flight originated at SWO, approximately 1745. In a telephone conversation with an NTSB representative, the 26-hour student pilot reported that prior to his departure from SWO on his second solo flight, he performed four takeoffs and landings on Runway 17 (a 7,401 by 100-feet asphalt runway) at SWO with his instructor on board. The student then dropped off the instructor and proceeded to make four successful solo landings on Runway 17 at SWO. He reported that on his fifth solo landing, he touched down slightly to the right of the center line. He felt the main wheels touch down, followed by the nose wheel. At that time, "the airplane made a sharp turn to the left." The student pilot thought that he still had some throttle in, and he applied right rudder. He "felt the airplane tip to the left" and was afraid that the airplane "might tip over," so he proceeded off the runway. After exiting the runway, the left main landing gear collided with an airport directional sign. The airplane then came to a stop. The pilot performed the proper shut-down procedures, contacted the tower to report the accident, and exited the airplane, uninjured. When asked how this accident could have been prevented, the pilot stated, "proper use of the rudder pedals to maintain center line." A review of pictures of the airplane was structural damage to the fuselage where the left main landing gear attached. The automated surface observation system at SWO was being serviced at the time of the accident, therefore, a local weather report could not be obtained. The student pilot and instructor reported that the wind at SWO was from approximately 160 degrees at 8-10 knots at the time of the accident. At 1853, the automated weather observing system at the Ponca City Regional Airport (PNC), near Ponca City, Oklahoma, located approximately 34 nautical miles north of SWO, reported wind from 120 degrees at 9 knots, 10 statute miles visibility, a clear sky, temperature 70 degrees Fahrenheit, dew point 46 degrees Fahrenheit, and a barometric pressure setting of 29.76 inches of Mercury.