This document outlines the engineering evaluation appropriate for modifying or replacing components of a previously certified seat when the certification process is based on qualification to the requirements of AS8049@ which includes dynamic testing. The engineering evaluation presented in this document may be used to determine if a modification (including replacement of a component) is a minor change with respect to meeting the dynamic testing requirements described in AS8049. Whenever a modification is considered@ the ability to meet all requirements of the applicable Federal Aviation Regulation (FAR) must be verified. For example@ this would include the capability to meet requirements such as flammability and flotation. Analysis and/or test data supporting the ability of the new materials and/or configuration to meet the applicable requirements must be submitted with the change documentation. This document addresses the evaluation of seat pan cushions@ secondary components@ and ancillary components. Other primary components such as restraint systems and primary structural components are not considered.