Reliability Case History of an Airborne Air Data Computer

The life of an airborne Air Data computer and some of its components have been observed in the field and in the laboratory. This paper treats 3 aspects of the reliability. Part 1 shows the relationship of predicted to actual MTBF and explains some seasonal fluctuations in actual MTBF. Monthly and yearly fluctuations are also explored. Part 2 shows some effects of workmanship-in-repair on reliability growth. The repair procedure was changed and the reliability gradually improved over a long period of time. Part 3 treats one of the components, a wirewound potentiometer, in some detail. A failure analysis and an improvement program are described.