Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 46.9; Flight Crew Total 858.3; Flight Crew Type 181.8
Situational Awareness
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Aircraft Equipment Problem Dissipated; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance; General Declared Emergency; General Maintenance Action
Aircraft
I was cruising at 7;000 FT on an IFR flight plan in clear conditions flying direct to my destination. While in contact with Approach Control; the engine suddenly began to run rough. I immediately initiated a 160 degree left hand turn to be on course directly to the nearest airport. I contacted Approach and declared an emergency due to a rough running engine. Approximately 20 - 30 seconds after the engine started running rough; the engine returned to running smooth again with all engine instruments indicating in the normal operating range. I informed Approach that the engine returned to normal operation and they asked me if I wanted to continue on to the nearest airport or fly to my original destination. I requested to continue on to my destination and landed without incident. After landing and taxiing to the ramp; I performed an engine run-up including a magneto check and found that the right magneto was not operating properly causing the engine to misfire. The aircraft was immediately grounded. Upon inspection by the mechanic; a bearing in the right magneto failed and caused the magneto to 'come apart'. Both the left and right magnetos were re-built and the aircraft has been returned to service. Although I followed the correct protocol of 'aviate; navigate; communicate;' I chose to disconnect the autopilot so that I could initiate the 160 degree turn to the nearest airport immediately. In doing so; with the distraction of making the turn; communicating with Approach; richening the mixture and reducing power; I climbed approximately 200 FT above my assigned altitude of 7;000 FT. In hindsight; if I had kept the autopilot engaged and input the nearest airport into the Garmin GNS 430 WAAS; my workload would have been reduced as I dealt with the emergency situation and I would not have climbed above my assigned altitude.
Cirrus pilot experiences a rough running engine while at 7;000 FT on an IFR flight plan and turns immediately toward a suitable airport then informs ATC. After 30 seconds the engine smooths out and the reporter elects to continue to destination. After landing a faulty magneto is determined to be the cause of the engine anomalies.