Spark Plug Servicing and ReplacementWritten by Michael Berry
Spark plug replacement and cleaning is a task that aircraft owners and pilots can easily do to maintain engine efficiency. I encourage aircraft owners to get involved in the maintenance of their aircraft, as a pilot aware of the mechanics of his or her aircraft is a safer pilot.
A component of maintaining an aircraft engine in good condition includes the regular removal, cleaning/inspection or replacement of the spark plugs as allowed by FAR 43 Appendix A (“Major Alterations, Major Repairs and Preventive Maintenance”).
Spark plugs wear out but can also just become dirty with use; they can become lead-fouled as well. Cylinder and engine problems can be identified by just looking at the tip of the spark plug.
Spark plugs, to be maintained in the optimum condition, need to be cleaned and re-gapped at no more than 100 hours (or as needed), tested and replaced when necessary. Some aircraft engines prone to lead fouling may require more frequent service to remove lead deposits.