||MIL-HDBK-338B: Electronic Reliability Design Handbook
This handbook is approved for
use by all Departments and Agencies of the Department of Defense (DoD). It
was developed by the DoD with the assistance of the military departments,
federal agencies, and industry and replaces in its entirety MIL-HDBK-338A.
The handbook is written for reliability managers and engineers and provides
guidance in developing and implementing a sound reliability program for all
types of products.
This Handbook is for guidance
only. This Handbook cannot be cited as a requirement. If it is, the
contractor does not have to comply.
Reliability is a discipline
that continues to increase in importance as systems become more complex,
support costs increase, and defense budgets decrease. Reliability has been a
recognized performance factor for at least 50 years. During World War II,
the V-1 missile team, led by Dr. Wernher von Braun, developed what was
probably the first reliability model. The model was based on a theory
advanced by Eric Pieruschka that if the probability of survival of an
element is 1/x, then the probability that a set of n identical elements will
survive is (1/x)n . The formula derived from this theory is sometimes called
Lusser’s law (Robert Lusser is considered a pioneer of reliability) but is
more frequently known as the formula for the reliability of a series system:
Rs = R1 x R2 x . . x Rn.
Despite the long gestation
period for reliability, achieving the high levels needed in military systems
is too often an elusive goal. System complexity, competing performance
requirements, the rush to incorporate promising but immature technologies,
and the pressures of acquisition budget and schedule contribute to this
elusiveness. In the commercial sector, high levels of reliability are also
necessary. Recently, American products once shunned in favor of foreign
alternatives have made or are making a comeback. This shift in consumer
preferences is directly attributable to significant improvements in the
reliability and quality of the American products.
Noting these improvements, and
facing a shrinking defense budget, the Department of Defense began the
process of changing its acquisition policies to buy more commercial
off-the-shelf products and to use commercial specifications and standards.
The objective is to capitalize on the “best practices” that American
business has developed or adopted, primarily in response to foreign
competitive pressures. When combined with the knowledge and expertise of
military contractors in building complex and effective military systems
(soundly demonstrated during the conflict with Iraq), it is hoped that these
commercial practices will allow the Department of Defense to acquire
world-class systems on time and within budget.
The information in this Handbook reflects the move
within the military to incorporate best commercial practices and the lessons
learned over many years of acquiring weapon systems “by the book”. Military
as well as commercial standards and handbooks are cited for reference
because they are familiar to both military and commercial companies. Many of
the military documents are being rescinded, so copies may be difficult to
obtain. For those who have copies or can obtain them, the military documents
provide a wealth of valuable information.
Beneficial comments (recommendations, additions, deletions)
and any pertinent data which may be useful in improving this document should
be addressed to: Air Force Research Laboratory/IFTB, 525 Brooks Road, Rome,
NY 13441-4505. Comments should be submitted using the self-addressed
Standardization Document Improvement Proposal (DD Form 1426) appearing at
the end of this document or by