On June 28, 1997, at 0700 hours mountain standard time, a Cessna 150F, N6634F, collided with a ditch following an on-ground loss of control while landing at Casa Grande, Arizona. The aircraft sustained substantial damage and the student pilot was not injured. The aircraft was operated by the pilot as a instructional flight under 14 CFR Part 91 when the accident occurred. The flight originated in Yuma, Arizona, at an undetermined time. Visual meteorological conditions prevailed. The student pilot was conducting her second supervised solo instructional flight when the accident occurred. The student pilot stated in her report that she set the aircraft down easy and straight on the runway. After it was on the ground, the aircraft "broke hard right," so she held the left rudder in to compensate with no success. She then said she tried to "clean up the plane" but it went out of control and ended up in a gully. The FAA Airworthiness Inspector who examined the aircraft after the accident stated that he was able to establish rudder continuity. Additionally, he did not find any preimpact damage to the landing gear, brakes, or nose landing gear. He did report that he found the stall warning system placarded inoperative. According to the student pilot's logbook entries, she had logged over 49 hours of dual instruction with 6 hours of flight time with the instructor who approved her solo flights.