reliability engineering for maintenance

Suppliers have two strategies for testing: 1) test for success and 2) test for failures. Reliability testing produces failures, particularly when the tests are accelerated with extra loads, and this may be troublesome to have in the records for future lawsuits. Thus it is often to everyone's advantage to perform reliability test under code names to protect against the broad rules of legal discovery.

Probability plots make sense of the chaos of failure data on an X-Y plot.

Most business decision have considerable uncertainty which implies at least two outcomes if you choose a course of action. Making decisions in the face of uncertainty requires the costs for taking action and the probability along with the cost for not taking action and the probability of the occurrence. In most cases the probabilities are not well known (maybe to one significant digit) and the costs are not well know (maybe to $10000). The quantitative assessment is called risk assessment. The issue is to take these not well identified issues and devise a strategy which can minimize exposure to risk for the business. The graphical representation of the methodology is called decision trees to reach the expected values for decision to take/not-take action.

The measure of the ability of an item to be retained in or restored to specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources.

Say what you want and want what you say to your vendors. Provide explanations of the objectives in contracts in terms the vendors will understand.

Reliability audits verify your reliability program is effective and find areas of weakness for corrective action. They are inquiries by factual examination of elements of the system with a written an objective criteria for performance beginning with an assessment of how management is involved and are they effective in building an productive reliability program.

The smartest way to maintain a reliability database is in Weibull format and Weibull databases are available.

Lognormal distributions are continuous life functions that have long tails to the right (display positive skewness) in time or usage. A lognormal distribution plotted on semi-log papers would appear as a normal curve.

Overall equipment effectiveness (OEE) is a manufacturing index to reduce complexity of discrete systems for problem solving and benchmarking.

Reliability-Centered maintenance (RCM) is a systematic planning process used to determine the maintenance requirements for a system. RCM expects the system has an inherent reliability and maintenance requirements are imposed upon the baseline of inherent safety and inherent reliability which can be no better than the worst than designed into the system.

Reliability is the probability that a device, system, or process will perform its prescribed duty without failure for a given time when operated correctly in a specified environment.

The International Electrical Congress (IEC) defines dependability as "Dependability describes the availability performance and its influencing factors: reliability performance, maintainability performance and maintenance support performance." MIL-HDBK-338 defines dependability differently as a measure of the degree to which an item is operable and capable of performing its required function at any (random) time during a specified mission profile, given that the item is available at mission start. (Item state during a mission includes the combined effects of the mission-related system R&M parameters but excludes non-mission time; see availability.) Dependability is related to reliability with the intention that dependability would be a more general concept than the measurable issues of reliability, maintainability, and maintenance.