Development of an advanced failure detection algorithm for the SSME

Since ground testing of the Space Shuttle Main Engine began in 1975, a multifaceted detection/shutdown system has been used to detect engine anomalies and initiate shutdown. In spite of this system, 27 major incidents have occurred since testing began. Although a small percentage of over 1200 successful hot fire tests, such incidents can result in significant cost and schedule impacts. Therefore, an advanced failure detection algorithm has been developed which consists of three detection approaches designed for a failure characteristic that has been previously documented. Simulations using sensor data from five incident tests show the algorithm detecting an anomally and signalling shutdown prior to the redline cutoff time. The foundation elements of the algorithm and its functioning are described.