FAA Publishes Airworthiness Concern Sheet on Tempest Spark Plugs

The FAA has issued an airworthiness concern sheet (ACS) for cracks found in the “Hot Lock Assembly” of certain Tempest brand spark plugs. The ACS follows a service bulletin issued by Tempest concerning certain plugs manufactured between May 5 and July 29, 2026. The cracking could potentially lead to the failure of the spark plug in service. Tempest stated in their service bulletin that they have identified and corrected the root cause of the issue, and published in the bulletin the part and lot numbers known to be affected.

Members are encouraged to review both the service bulletin and the ACS, and report any findings from the field to the FAA. The ACS process is an important way for the FAA and the aviation community to work together to ensure continued operational safety. It is non-regulatory and helps the FAA to gather data on airworthiness issues in the field.