This project ventures into the domain of software maintenance methodologies, an area given relatively little attention in software engineering. Project efforts are divided into three tasks: (1) definition of maintenance methodology requirements; (2) development of a model of the AEGIS maintenance process; and (3) specification of the requirements for an AEGIS maintenance methodology. The focus of this report is on the third task. The research utilizes the Objectives/Principles/Attributes (OPA) framework developed for software quality assessment for time-critical, embedded systems. The overriding maintenance objective is to "realize desired changes in an efficient and effective manner." Four principles are identified that support achievement of this objective. Eleven requirements are derived for an AEGIS maintenance methodology. The AEGIS maintenance process model is used to determine the potential points where any of the requirements can be met. Recommendations are made with respect to restructuring the process, noting the most appropriate place for meeting requirements, and acquisition or development of software utilities to support maintenance. Recommended as an approach for meeting long-term needs is the AEGIS System Evolution Environment, supporting both systems and software maintenance activities. [Appendices Not Included]