Abstract : Validation of Maintainability Prediction Techniques prescribed in RADC-TR-78-169 was performed. The techniques for preliminary and detailed prediction were applied to three (3) representative samples of electronic equipment. The detailed predictions were then compared with demonstrated field performance on equipments that have in excess of one million system hours of combined operation. The new time synthesis prediction technique proved to a be a distinct improvement in maintainability prediction methodology over existing techniques. In addition, the time synthesis model provides a structured means of assessing the maintainability design in its early and final stages, thereby, determining if the system maintainability requirements will be achieved. Maintainability, as with all technologies, is continuously changing. It is recommended that Maintainability Standards be established in the areas of Built-In-Test (BIT), Fault Tolerant Circuitry, Self-Test/Self-Diagnosis capability to meet the needs of maintainability in the future. (Author)