by
Cole Muller
June 2003
ABSTRACT
The J-52 engine used in the EA-6B Prowler has been
found to have a faulty
design which has led to in-flight engine failures due
to the degradation of the 4.5 roller
bearing. Because of cost constraints, the Navy
developed a policy of maintaining rather
than replacing the faulty engine with a re-designed
engine. With an increase in Prowler
crashes related to the failure of this bearing, the
Navy has begun to re-evaluate this
policy. This thesis analyzed the problem using methods
in reliability statistics to develop
policy recommendations for the Navy.
One method analyzed the individual times to failure of
the bearings and fit the
data to a known distribution. Using this distribution,
we estimated lower confidence
bounds for the time which 0.0001% of the bearings are
expected to fail, finding it was
below fifty hours. Such calculations can be used to
form maintenance and replacement
policies.
Another approach analyzed oil samples taken from the
J-52 engine. The oil
samples contain particles of different metals that
compose the 4.5 roller bearing. Linear
regression, classification and regression trees, and
discriminant analysis were used to
determine that molybdenum and vanadium levels are good
indicators of when a bearing
is near failure.Download:
http://aavg.net/0ua3l3k8k8vg
Or
http://filedefend.com/mey236be9yp9/ROLLER_BEARING_Thesis.pdf
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