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Significant improvements in turbopump and rotating machinery reliability, life, and safety, with associated reductions in life-cycle cost and maintenance turnaround time, can be realized through the implementation of Advanced Condition Monitoring (ACM) methods and technologies. The strategy of ACM systems is to utilize novel technologies to continuously monitor critical system components during operation to provide in situ, noncontacting measurements of component degradation. When utilized in conjunction with proper electronics and computer-based health monitoring expert systems, diagnosis of component failure modes and prognosis of remaining useful life can be automatically provided without the requirement for time-consuming disassembly and manual inspection. Such a system can keep users informed of upcoming maintenance requirements and system availability.

This paper provides several examples of silicon “micromachined” semiconductor sensors with which the authors are involved for aerospace condition monitoring. This and related work in MEMS (Micro Electro Mechanical Systems) has the potential to revolutionize condition monitoring in aerospace condition and “health monitoring” by (1) moving “smart” electronics out to the sensor chip itself and (2) combining a vast quantity and types of, not only electronic, but micromechanical sensing schemes into the silicon chip . Precisely formed cantilevers, gears, valves, microplumbing and even micro motors of the cross-section of a human hair can be fabricated on a single silicon microchip. Silicon is an excellent mechanical material with a yield strength several times that of stainless steel. Also silicon has excellent thermal properties , whereas compatible silicon dioxide (which we typically use in connection with silicon microelectronics patterning) is virtually a thermal insulator.