What happened
On November 16, 2001, the pilot prepared to depart from McCollum Field. During an engine runup, the pilot discovered the left magneto was inoperative. After a mechanic disconnected and reconnected the "P" leads, the left magneto resumed operation. The pilot subsequently flew to Peachtree City and then to Tara Field in Hampton, Georgia.
Upon departing Tara Field, the pilot found the left magneto was again inoperative. Following instructions from a mechanic to disconnect the "P" leads and return home, the pilot proceeded with the takeoff. While the engine initially developed full power with normal exhaust gas temperature (EGT), approximately five minutes after departure, the EGT rose significantly and one magneto failed. About one minute later, the engine stopped functioning entirely.
The pilot was unable to reach Peachtree City via radar vectors provided by Atlanta Approach and instead performed an emergency landing in a field with the landing gear down and full flaps extended. During the rollout, the aircraft collided with a drainage ditch, causing the landing gear to collapse before the aircraft slid to a stop. The pilot was not injured.
The investigation
The magnetos had been overhauled approximately 100 flight hours prior to the accident. An examination of the engine revealed that the "P" lead was disconnected from the right magneto and the spark retard lead was disconnected from the left magneto. Upon reconnecting these leads and starting the engine, only the right magneto functioned. The engine was operated to 1,500 RPM with a club propeller in the feathered position, and no mechanical failure or malfunction of the engine assembly was found.
Testing at the manufacturer's facility determined that the left magneto condenser was inoperative. Manufacturer personnel noted that when the "P" lead is removed from these magnetos, they can ground internally and become inoperative, though contamination can sometimes delay this process.