On August 4, 2011, about 1830 central daylight time, an Aerosport Ikarus C42E, N577JP, landed hard and subsequently went off the left side of the runway and struck a ditch resulting in substantial damage. The airplane was landing on runway 8 at the East Troy Municipal Airport, East Troy, Wisconsin, when the accident occurred. The student pilot and the flight instructor were not injured. The airplane was registered to Tenerelli LLC, and operated as an instructional flight under the provisions of 14 Code of Federal Regulations Part 91. Visual flight rules (VFR) conditions prevailed for the flight, which was not operating on a flight plan. The local flight originated about 1750. The certificated flight instructor reported that the student pilot made a hard landing and the airplane bounced and became airborne again. He said that the student reached for the door and the airplane then yawed off the left side of the runway and impacted a ditch. The flight instructor listed no mechanical malfunctions of the airplane. The student pilot reported that the accident landing was his fourth landing. He said that the landing was hard and the airplane bounced. He stated that he added power and at about the same time, his door came open. He said that he initially ignored the door but felt that the open door was causing the airplane to yaw to the left. He then tried to close the door and the airplane went off of the runway. The student pilot listed "unknown" in regard to any mechanical malfunctions of the airplane. Examination of the airplane after the accident revealed propeller damage, separated left main landing gear, collapsed nose landing gear, a fractured main keel tube in the fuselage, and a bent fuselage. No preimpact anomalies were found.