On June 28, 2009, at 2125 eastern daylight time, a Champion 7GCAA single-engine airplane, N9085L, sustained substantial damage during a forced landing to a field near Shelbyville, Indiana. The airline transport pilot was not injured and the student pilot sustained minor injuries. The airplane was registered to Tecumseh Aircraft Partners, LLC, San Diego, California, and operated by the pilot. Visual meteorological conditions prevailed and a flight plan was not filed for the Code of Federal Regulations Part 91 flight. The flight departed Boggstown, Indiana, at 2020, and was destined for Columbus, Indiana. According to the pilot, who was seated in the rear seat, he and the student pilot had completed several landings at various airports in the area. After departure from Boggstown, at 1,100 feet mean sea level (msl), the pilot pulled the engine power to idle to practice a simulated engine out maneuver. At 150 feet above ground level, the pilot increased the engine power; however, the engine did not respond. The pilot then attempted a forced landing to a field. During the landing flare, "the engine tried to come back..." After touchdown, the airplane ground looped and sustained substantial damage. The pilot reported to the Federal Aviation Administration (FAA) that the flight was a personal flight, and not an instructional flight. The pilot did not have a flight instructor certificate for single-engine airplanes. The pilot also reported to the FAA that had the airplane not been damaged during the forced landing, he would have restarted the engine in the field and departed to his intended destination. According to local authorities who were the first responders to the accident site, the pilot reported to them that "he was instructing [the student pilot] in a maneuver for engine failure/shutdown and also touch and go landings." The pilot reported he had accumulated a total of 4 hours in the accident airplane. Examination of the airplane by FAA inspectors revealed the left main landing gear separated from the fuselage, the right main wing spar was broken, and one propeller blade was bent aft. The engine controls, flight instruments, fuel selector, and elevator trim were accessible only by the front seat position, the rear seat position had access only to the throttle and carburetor heat controls. The airplane was recovered for further examination. Examination of the engine at the accident site by FAA inspectors revealed no anomalies that would have precluded normal engine operation. On July 9, 2009, the NTSB investigator-in-charge received a telephone call from the FAA inspector, who was assigned to the accident investigation, regarding a fractured landing gear attach thru-bolt. According to the inspector, the mechanic who recovered the airplane from the field contacted him and stated he observed the left main landing gear attach thru-bolt on the accident airplane had a preexisting crack which led to the failure of the left main landing gear during the forced landing. The fractured bolt was retained by the FAA and forwarded to the NTSB materials laboratory for further examination. NTSB materials laboratory examination of the landing gear attach bolt showed the bolt shank contained a preexisting crack; however, the fracture surface contained corrosion. After cleaning the fracture surface, the bolt fracture surface contained signatures consistent with fatigue and overload. According to the airframe manufacturer service letter, at every 500 hour interval, the landing gear attach bolt was to be removed and replaced, or inspected with a magnetic particle inspection. Examination of the airframe records showed that this service letter had not been accomplished in the preceding 500 hours. The airframe records also showed the airplane's last annual inspection had been completed in August 2007, and not within the preceding 12 months. The FAA inspector reported that prior to the flight, the pilot had not reviewed the airplane logbooks to determine if the airplane was airworthy. On August 7, 2009, two additional FAA inspectors examined the engine. Mechanical continuity was noted in the engine and accessories. The carburetor had been previously removed and disassembled by the cargo company director of maintenance. Examination of the carburetor revealed the mixture control cable was broken near the carburetor control arm attach point, and the carburetor attach hardware and remained cable were found secure. The cable fracture surfaces contained oxidation. The director of maintenance stated that he thought the mixture cable was just loose and had not broken the cable when he removed the carburetor. Inspection of the carburetor showed the carburetor inside throat area was covered in black soot.