One-Only STC

A “One-only” STC may be issued for a particular aircraft, identified by make, model, and serial number.  A one-only STC cannot be amended and the holder is not eligible for production approval.  Application for a multiple STC is required for subsequent approvals of the modification. 

Non-Interference STC

A non-interference, or no-hazard, STC addresses a convenience function modification that is not required by the applicable airworthiness standards. The STC Limitations and Conditions section specifies the extent, or limitation, of the modification approved by the FAA.