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A testbed for implementing prognostic methodologies on cryogenic propellant loading systems

Prognostic technology determines the health state of a system and estimates its remaining useful life. With this information, operators can make decisions on how to operate the system such that it minimizes life cycle cost and maximizes safety. The individual decisions can range from changes to control settings to scheduling future operations or to determining the best repair and maintenance activities. Fault injection experiments on test beds that represent key subsystems are critical for the maturation of both the sub-systems themselves as well as the prognostic technology. It is necessary to precisely emulate actual fault conditions to maximize the utility for validation of hardware and software. Representative of such a test environment, we present here the development of a testbed for pneumatic valves, which are used in cryogenic propellant loading systems. The pneumatic valve testbed allows for the injection of magnitude-varying leaks that follow specified damage progression profiles in order to emulate the evolution (on a compressed time scale) of common valve faults. Besides the various leakage faults, the testbed also allows exploration of battery degradation on the operation of the valves. Experimental results and progress towards the maturation and validation of component-level prognostic methods are discussed in the context of cryogenic refueling operations.