During testing of compressors under start/stop conditions, several helical suspension springs failed. The ensuing failure investigation showed that the springs failed due to fatigue. The analysis showed that during start/stop testing the springs would undergo both a lateral and axial deflection, greatly increasing the torsional stresses on the spring. To understand the fatigue limits under these test conditions, a bench test was used to establish the fatigue strength of the springs. The bench tests showed that the failed springs had an unacceptable surface texture that reduced the fatigue life. Based on an understanding of the compressor motion, a Monte...