A “Service Bulletin“ is the equivalent of an “AD“ (Airworthiness Directive) on a Certified Aircraft. In the Experimental Regulations, no channel exists for AD’s, as such we call them Service Bulletins. These items are considered MANDATORY airworthiness items that should be fixed according to the Service Bulletin information.
A Service Letter is either a suggested change or designed as an assistant to the owner for an area where multiple difficulties arise.
* Pricing Information expires 90 days after the date of the issue of a Service Bulletin.