{"id":1449,"date":"2011-06-02T16:31:23","date_gmt":"2011-06-02T21:31:23","guid":{"rendered":"http:\/\/www.livingreliability.com\/en\/?p=1449"},"modified":"2025-11-06T05:56:05","modified_gmt":"2025-11-06T10:56:05","slug":"failure-analysis-for-reliability-analysis","status":"publish","type":"post","link":"https:\/\/www.livingreliability.com\/en\/posts\/failure-analysis-for-reliability-analysis\/","title":{"rendered":"Failure analysis for reliability analysis"},"content":{"rendered":"

The dismantling of an Engine can occur for one of several reasons, for example, as a result of\u00a0failure, symptoms of impending failure, or because the unit has reached its predetermined\u00a0 age of overhaul. For whatever reason an overhaul\u00a0 represents a golden opportunity to enhance the performance of\u00a0 predictive maintenance. The observations made during rebuild are\u00a0indispensable\u00a0for CBM optimization through EXAKT analysis. The overhaul reveals\u00a0a set of clear life cycle sample points at the failure mode level.<\/em><\/p>\n

A Failure Mode is an event\u00a0that causes a\u00a0change\u00a0in a part resulting\u00a0in the loss of a required system function. Failure modes of a major component (for example, an engine, or\u00a0a final drive)\u00a0\u00a0can be identified accurately only upon disassembly. We must not presume that when an equipment in the fleet exhibits a symptom, for example an anomolous vital sign or a high oil analysis result,\u00a0that this alone determines a failure sample point for an EXAKT model. The failure must be confirmed <\/em>visually by the rebuilders or failure analysts. Only then should it be used as a point in a sample for any kind of reliability analysis.<\/p>\n

Conversely, an engine that is rebuilt as a result of having reached its predetermined useful life could still, neverthless, present damage or advanced wear to the extent that it is judged to have “potentially” failed.\u00a0That is,\u00a0failure is considered, in the judgment of the technicians or failure analyst,\u00a0imminent within hours or days. Obviously, to make such a judgment, the organization must, through consensus among technicians and failure analysts, gradually develop standards for distinguishing between suspension and failure. Photographic records and other rich information are helpful.<\/p>\n\n\n\n\n
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The scheduled disassembly of an Engine at age 18988 hours detected advanced wear of the connecting rod bearings at positions 7 and 8. The photos show the condition of the crankshift at position B7-A7 and the connecting rod bearings at positions B7-A7, B8-A8. At the other crankshaft postions wear was much less pronunced\u00a0and considered\u00a0“normal”.<\/p>\n

The failure analysts can usually identify the failure mode directly responsible for failure. In addition\u00a0they may also identify potential failures occurring elsewhere in the engine. A standardized investigative process provides the detailed information about the engine’s actual state at the moment of disassembly.\u00a0 The true states of each relevant failure mode\u00a0constitute\u00a0 sample points for the development of a decision model. The more accurate the identification of the failure mode and its ending event (Failure or Suspension), the more confidence can be entrusted to the decisions flowing from the model.<\/p>\n

A disassembled engine, whether it\u00a0has failed functionally or not, \u00a0is a rich source of information vital to reliability analysis. The engine\u00a0reveals its secrets\u00a0of failure mode behavior\u00a0completely for us. Typically however, Engines which have completed their scheduled life prior to rebuild are not subjected to failure analysis.\u00a0 Consequently it is assumed, mistakenly that all failure modes in the engine were suspended rather than to have potentially failed. The error of this assumption\u00a0is clear in the case depicted above. Ignoring or mistaking potential failure for suspension and will\u00a0result in CBM decsion models having\u00a0poor prediction performance.<\/p>\n\n","protected":false},"excerpt":{"rendered":"

The dismantling of an Engine can occur for one of several reasons, for example, as a result of\u00a0failure, symptoms of impending failure, or because the unit has reached its predetermined\u00a0 age of overhaul. For whatever reason an overhaul\u00a0 represents a golden opportunity to enhance the performance of\u00a0 predictive maintenance. The observations made during rebuild are\u00a0indispensable\u00a0for […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[89],"tags":[],"class_list":["post-1449","post","type-post","status-publish","format-standard","hentry","category-theory-and-definitions"],"_links":{"self":[{"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/posts\/1449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/comments?post=1449"}],"version-history":[{"count":1,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/posts\/1449\/revisions"}],"predecessor-version":[{"id":8740,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/posts\/1449\/revisions\/8740"}],"wp:attachment":[{"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/media?parent=1449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/categories?post=1449"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.livingreliability.com\/en\/wp-json\/wp\/v2\/tags?post=1449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}