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An Environmental Control and Life Support System (ECLSS) functional behavior model has been developed for the Stage 6 assembly of Space Station Freedom (SSF) using RDD-100®. This software tool has been used to generate, both in graphic and text formats, system and subsystem descriptions of the ECLSS functional behavior. Program requirements have been traced to the ECLSS functions and the functions are then allocated to system components. Thus, RDD-100® provides a means of verifying that documented requirements are linked to the actual hardware. The model is termed a behavior model because it defines the specific behavior characteristics and functional properties of the ECLSS. Functional elements are graphically arranged to show operating sequences and relationships and are specified in terms of input items, transformations, output items and performance objectives.

Procedures that have been developed as part of the NASA JSC-sponsored pre-prototype Checkout, Servicing and Maintenance (COSM) program for pre- and post-EVA airlock operations are described. This paper addresses the accompanying pressure changes in the airlock and in the Advanced Extravehicular Mobility Unit (EMU). Additionally, the paper focuses on the components that are checked out, and includes the step-by-step sequences to be followed by the crew, the required screen displays and prompts that accompany each step, and a description of the automated processes that occur.