||TAAF Process: A Technical Brief for TAAF Implementation
TAAF Process: IC. WHAT IS THE TAAF PROCESS?
IC. What is the TAAF Process?
The TAAF process is an iterative, closed-loop reliability growth
methodology. TAAF is accomplished primarily during full-scale engineering
development (FSED). The process includes testing, analyzing test failures to
determine cause of failure, redesigning to remove the cause, implementing the
new design, and retesting to verify that the failure cause has been
TAAF is necessary because, even with the very best of modern engineering
methods, initial designs for systems that are complex or that involve new
technology have reliability deficiencies that are difficult to fully detect
and eliminate through design analysis. The TAAF process should surface these
problems early and eliminate them before rate production.
The heart of the TAAF process is the identification of reliability
weaknesses. TAAF includes both formal and informal means for doing so. The
formal aspect is called a Reliability Development Test (RDT), or sometimes a
Reliability Development/Growth Test (RD/GT), and involves dedicated long term
exposure of system equipment to simulated mission profile environments (See
Appendix A - Glossary). The informal means is the systematic identification of
reliability problems found during other activities such as systems
integration, subsystem/component development testing, environmental
qualification testing, and operational/field testing. Both means are essential
to the TAAF process and are illustrated in Figure 1.
The RDT portion of the TAAF process, because it requires system hardware,
test chambers, and similar resources, is necessarily a major investment. Thus,
RDT is not a substitute for the disciplined design and design analysis
process; it is a complement to R.
A well executed RDT program will get much better results than traditional
reliability demonstration tests because the incentives are different. The
purpose of RDT is not to "prove" that a mean-time-between-failure threshold
has been met but rather to deliberately search out and eliminate deficiencies.
In RDT, failures are analyzed and corrected, not scored. Tenfold improvements
in reliability are not unusual for a well-executed TAAF program. However, the
amount of reliability growth that the TAAF process will provide depends on the
stage of development and the technology. The more immature the technology, the
greater the need for RDT.
The TAAF process, as described in this guide, is principally intended to
eliminate hardware reliability weaknesses by empirical means. A large percent
of today's military equipment includes software. The general approach and
acquisition methods presented in this technical brief should be a starting
point for structuring a software TAAF process, but implementation will require