Accident Overview
On June 28, 2009, at 2125 eastern daylight time, a Champion 7GCAA single-engine airplane, registration N9085L, sustained substantial damage during a forced landing to a field near Shelbyville, Indiana. The airplane was operated by the pilot under Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Boggstown, Indiana, at 2020, with Columbus, Indiana, as the intended destination.
Flight History
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.
Pilot Information
The pilot reported to the Federal Aviation Administration (FAA) that the flight was a personal flight, not an instructional flight. The pilot did not hold a flight instructor certificate for single-engine airplanes. He reported having accumulated a total of 4 hours in the accident airplane. According to local authorities who were the first responders, the pilot reported that "he was instructing [the student pilot] in a maneuver for engine failure/shutdown and also touch and go landings."
The pilot also stated 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.
Post-Accident Examination
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 from 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 regarding a fractured landing gear attach thru-bolt. According to the inspector, the mechanic who recovered the airplane from the field observed that the left main landing gear attach thru-bolt 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.
Maintenance Findings
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 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 remaining 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.