Purpose of Document

This document describes a method of identifying the modification status of aircraft components with regard to the Service Bulletins (SB) that have been issued for the equipment.

A mod is the incorporation of an approved Type Design change into a component that is already certified and in service that maintains component interchangeability. That means it still meets the form, fit, function equivalence for the component with and without the mod. A mod is not appropriate for a change to a component that does not result in a form, fit, function equivalent, a part number roll is preferred when the result does change the form, fit, or function. A mod as defined here does not require a part number roll.

The details of a mod are documented in a Service Bulletin (SB) which identifies the details of the modification (parts, procedures, etc.) as well as the methods of identification that are to be used to indicate that the mod has been implemented.

The determination of interchangeability can be a complex topic involving multiple parties (supplier, aircraft manufacturer, airworthiness authorities) and is beyond the scope of this document. It is assumed that if an SB with Mod Status indication is to be created, it has already been determined that the components are interchangeable.