Using test data to predict avionics integrity

Published data on avionic fatigue life and high-temperature endurance were used to develop straight-line relationships between stress amplitudes and life at given amplitudes for four part types: a chassis, a plated-through hole, an integrated circuit (IC), and a non-IC piece part. Design-life-distributions for four accelerated reliability test programs were derived for the same item categories using the same straight-line relationships between stress and life. The tests involved 15 specimens and approximately 40000 accelerated test hours. A test-life observation was multiplied by the ratio between predicted usage life mean for the design configuration and predicted test-life mean for the test configuration being observed. A product limit technique was used to treat censorship (observations of test end without relevant failure). The resulting test data distribution was used to predict the failure-free operation period and the mean time between failures for the new design.<>