Accident Overview
On July 16, 2014, at approximately 1450 eastern daylight time, a Cessna 172N airplane, registration N13SK, sustained substantial damage during a forced landing near Rockville, Indiana. The pilot and passenger were not injured. The airplane was operated under 14 CFR Part 91 as a personal flight. Day visual meteorological conditions prevailed, and no flight plan was filed. The local flight had departed from a private airport near Rockville about 1400.
Engine Power Loss and Forced Landing
According to the pilot, the engine experienced a partial loss of power while in cruise flight. The pilot attempted to restore power by applying carburetor heat and checking the mixture and fuel selector positions, but engine performance continued to degrade. The pilot conducted a forced landing into a corn field, during which both wings were damaged.
Post-Accident Examination
During examination of the engine, investigators found that both points of the single drive/dual magneto system would not open; with the center cam rotated to the 'points open' position, both points remained closed. Further inspection revealed that four screws intended to hold the magneto points in their operational position had become loose. Two of the loose screws lacked torque paint, and the torque paint for the other two loose screws was missing from the screw slot.
Maintenance History
Aircraft records indicated that the airplane had flown eight hours since its last annual inspection on February 3, 2014. The investigation was unable to interview the mechanic who performed this annual inspection and recent maintenance on the airplane.