scope:

Design of vehicle propulsion systems requires explicit definition of fluid properties across component interfaces to ensure safety and reliability. The propellant delivery system components are designed and verified to these conditions. During a routine tanking operation on the Space Shuttle system, the inability to verify closure of a valve resulted in a launch scrub. A proper Failure Modes Effect Analysis/Critical Items List (FMEA/CIL) for each component requires explicit definition of fluid properties across component interfaces. Margin demonstration and off nominal component/system testing can be planned and executed to perform risk mitigation when compositions are identified.