Failure Analysis or Failure Diagnosis is the first step in identifying the correct solution to a problem to prevent it from happening again!
It is therefore a critical component of all reliability improvement processes, since if you cannot identify accurately what the problem is (or has been), then it is unlikely that you will be able to correctly identify the optimum, or even an effective solution.
When major or catastrophic plant or machinery failure occurs, identification of the root cause should form a mandatory component of the follow-up investigation activities. This will help failings in the plant, process or operating regime to be identified with confidence and eliminated from future operations. Where significant losses are involved, it will also help to identify who is responsible for the failure and therefore on whom the onus for re-instatement or compensation should fall.