R&M 2000 and Environmental Stress Screening

The United States Air Force, Army, and Navy have established the need for Environmental Stress Screening (ESS). The Air Force policy statement issued 1986 November imposed the provision that all fielded major electronic systems must deliver 2000 hours failure free. To accomplish this will require changes in design, producibility, and manufacturing attitudes. Defectives must be removed in the factory, at the most cost effective point in the production cycle. This will require assessing failures from the field, then developing a system to identify these defectives in the factory, at the lowest level of assembly. Poor reliability rooted in high component failure rates leads to premature equipment failures. Fielded systems and spares provisioning with resultant maintenance actions cost heavily during each year of life. The result is that the spares provisioning & logistic support is now exceeding 50 percent of the defense allocation (1984 and 1985 budgets). Cost increases result from poor equipment reliability. Today, systems originally contracted to deliver over 500 hours mean time-between-failures (MTBF) are delivering less than 50 hours MTBF, (Navy Maintenance Material Management ``3M´´ report). Excessive failure of components is a major cause of reduced life of equipment. Most maintenance actions involve the replacement of piece parts. The roots of this problem lie in the factory. Manufacturers are not removing defectives early in the product design/production cycle. Because of inadequate testing, most defectives are not detected in the factory. Failures are then precipitated in the field.