Accident Overview
While on approach to the airport, the airplane experienced a loss of engine power. The pilot executed a forced landing, during which the aircraft collided with the airport perimeter fence and came to rest inverted.
Inspection Findings
Initial inspection determined that the P-Lead for the dual magneto was not connected to the system properly. The left side magneto timing was found to be 10 degrees after top dead center, while the right side timing was within manufacturer's specifications. Further examination revealed that the points on the left side of the magneto were closed, rendering that side inoperative. A functional check of the ignition harness capacitors showed that when the ignition harness cover was secured to the magneto, the left capacitor was intermittent. When the cover was loosened, the left magneto functioned properly.
Service Bulletin Compliance
It was observed that Teledyne Continental Motors (TCM) Service Bulletin 662A (replacement of date code affected capacitors) and TCM Service Bulletin 651 (capacitor grounding wire and attaching wire routing) had not been complied with.
Manufacturer Examination
The magneto was sent to the manufacturer for further examination, which revealed that the primary ignition lead wire coil was misrouted from the terminal post to the distributor block. This misrouting allowed the wire to become trapped between the case halves when the cover was secured. When the wire was routed properly and bench tested, the magneto operated within manufacturer's specifications.
Maintenance History
Engine logbook entries indicated that two weeks prior to the accident, the engine would not run on the right magneto. A repair shop work order stated that the left side points were grounded, rendering that side inoperative. The points were readjusted and the magneto was retimed on both sides. The magneto was returned as serviceable and reinstalled on the engine, but the problem persisted. Subsequently, the ignition switch and magneto capacitor were replaced, and the right magneto P-Lead was repaired. The airplane was returned to service after a ground run revealed no mechanical anomalies.