Mechanical Failure Rates for Non-Electronic Reliability
233
Section III is from Earles, D., Eddins, M., and Jackson D. A theory of
component part life expectancies, 8th National Symposium on Reliability
and Quality Control, 1962.
II. FAILURE-RATE TABULATION
Table D.3 is a comprehensive tabulation of many different components and
their failure rates and has been compiled from an analysis of component
performance in actual applications. It should be noted that the following
severity factors KF, Table D.2, must be used in applying the failure rates
in order to take into account the effects of environment: Therefore, the failure rate
), ~- 2GKF
(D.2)
III. COMPONENT LIFE EXPECTATION
Table D.5 gives a comprehensive tabulation of life expectancies for many
different components. Systems-maintenance procedures should be based
upon these life expectancies. Where maintenance is not practical, such
as in space-vehicle applications, alternate-mode operation with appropriate
switching must be provided. This is necessary if the design cannot be
changed so as to utilize a longer-life component. It should be noted that
the life expectancy severity factors KL from Table D.4 must be used in
determining component life expectancies in order to take into account
the effects of the environment. Therefore, the wear-out life
tw = taKL
(D.3)
Table D.2 Severity factors KF
Laboratory computer
Ground equipment
Shipboard equipment
Trailer-mounted equipment
Rail-mounted equipment
Aircraft equipment (bench test)
Missile equipment (bench test)
Aircraft equipment (in flight)
Missile equipment (in flight)
1
10
20
25
30
50
75
lOO
1000