Thirty-six individual sensors are being tested and have accumulated between 900,000 and 1.4 million cycles each. There have been two minor (cable) failures at 900,000 hours and 950,000 hours. Based on this latest available test data, we can predict very conservatively that the MTBF of these non-repairable units is 2.56 million cycles and that, within an 80% confidence limit, the end-of-life for all units would be an average of 5 million cycles and some should last as long as 8 million cycles.
The paper goes on to examine the results of long-term reliabilitynendurance testing of a FUTEK sensor that has survivedm over 1 billion cycles of accelerated stress testing. The projected MTBF of that sensor type is 843 million cycles with a 95% confidence factor.