On September 24, 2003, at 1831 central daylight time, an Aeronca BL-7-AC, N83608, registered to and operated by a private pilot, collided with the ground at a sod farm southwest of Pell City, Alabama. The personal flight was operated under the provisions of Title 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The private pilot received serious injuries and the airplane sustained substantial damage. The flight departed Pell City Saint Clair County Airport, Pell City, Alabama, on September 24, 2003, at 1730. According to the pilot, the purpose of the flight was to practice flight maneuvers. While practicing a slip maneuver, the pilot states that the airplane's left wing and nose dropped abruptly to nearly vertical. The pilot then attempted to make corrections to establish normal flight attitude. The airplane stalled and collided with the ground in a three-point attitude. The pilot reported no mechanical problems with the airplane. The initial examination of the accident site showed the airplane collided with the ground 3 miles southwest of the Pell City Saint Clair Airport. Post-accident examination of airplane failed to disclose any mechanical problems. Examination of the airplane revealed that the spar of the right wing was bent, and the engine firewall was buckled.