MTBF Analysis

MTBF (Mean Time Between Failure) analyses predict the failure rate of the space power supply. Using mostly experiential information and methods derived from MIL-HDB-217, and drawing on the temperature and electrical stress levels derived from earlier analyses, the failure rate may be computed. Computer programs to perform the computation are available. Simplified assessments using only the parts count are possible. However, they are not as precise as the actual stress method. Clearly, the electrical stress and thermal stress of the piece parts must be determined to accurately predict MTBF.

FMECA (Failure Modes Effects Criticality Analysis) is often required to be performed for a space power supply, as this allows more reliable units to be achieved. A knowledge of the functional operation as well as the failure rate of each piece part is needed to prepare a FMECA. Therefore, the MTBF and all subsidiary analyses are required for a FMECA.