What happened
While operating in cruise flight at 2,500 feet, just past the Cedar Lake VOR, the pilot reported hearing a loud "pop" originating from the engine compartment. This was immediately followed by an immediate loss of power.
During the subsequent forced landing, the aircraft struck a large fence post. The impact caused the right wing to separate from the fuselage. Following the strike, the aircraft rotated 90 degrees and the landing gear collapsed.
The investigation
An examination of the aircraft revealed that the magneto had disconnected from the accessory gear box. Investigators inspected the magneto hold-down components and found that while the upper magneto hold-down stud remained intact with its associated nut, washer, lock washer, and hold-down clip properly installed, the hardware for the lower hold-down stud was missing. Additionally, a significant section of the fracture was noted on the magneto housing hold-down flange.