Service Bulletins & Letters

A Service Letter is normally used to pass information along to the industry from the manufacturer and are not mandatory. Service Bulletins are highlighting more important service difficulties found in the field. They can be labelled as Mandatory by the manufacturer, but still are not required to be performed on privately owned aircraft. Commercial operators are normally required to comply with mandatory SB’s by the regulatory authority (FAA, TC, EASA, etc.). Mandatory SB’s are often the basis of Airworthiness Directives published by the regulatory authority.