The Reliability Engineering Glossary
Reliability engineering and related fields use a vocabulary unique to our field of endeavor. For example, the term ‘reliability’ has the meaning of ‘trustworthy’ in everyday English use. For us, ‘reliability’ has a precise engineering definition.
Glossary description and plans
This glossary is meant to help us learn the language of reliability engineering. The category of ‘Terms’ is like a dictionary, including terms and their definitions as used by engineers. The category of ‘Methods’ is a listing of the techniques, tools, approaches, or concepts that may be found within a reliability plan. In the near future, we expect to expand the ‘Methods’ pages to include guidelines on use or application, examples, and additional references.
We also plan to expand the glossary to include formulas and failure mechanisms. Please let us know if there is another list of terms that should be added if you do not find a term that should be included or if you would like to recommend a change to an existing entry.
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- Failure in timeThe rate of expected failures per unit of time. Commonly used to represent the number of failures expected over one billion (109) device-hours of operation. The relationship of FIT to MTBF may be expressed as: MTBF = 1,000,000,000 x 1/FIT. Some use FIT with one million hours (106) instead. Read More
- Failure, independentFailure that occurs without being caused by the failure of any other item (not dependent). Read More
- Failure, intermittentFailure for a limited period of time, allowed by the item's recovery of its ability to perform within specified limits without any remedial action. Read More
- Failure mechanismA physical, chemical, electrical, thermal, or other process that results in failure. Read More
- Failure modeThe observable consequence of the mechanism through which the failure occurs, i.e., short, open, fracture, excessive wear, etc. Read More
- Failure mode and effects analysis (FMEA)A qualitative and systematic analysis method intended to identify, prioritize, and reduce technical risks of failures to an acceptable level, with emphasis on improving product design or manufacturing process. FMEA is a structured process used to identify and prioritize potential failure modes(...) Read More
- Failure, nonchargeableA nonrelevant failure or a relevant failure caused by a condition previously specified as not within the responsibility of a given organizational entity. Read More
- Failure, nonrelevantA failure verified as having been caused by a condition not present in the operational environment or a failure verified as peculiar to an item design that will not enter the operational inventory. Read More
- Failure observerThe person who is in a position to observe a failure, recognize it as such, and report it for correction. Read More
- Failure processThe interaction of stress and resistance to failure over time. Read More
- Failure, randomA failure whose occurrence is predictable only in a probabilistic or statistical sense and is applicable to all distributions. Read More
- Failure rateThe total number of failures within an item population, divided by the total number of life units expended by that population, during a particular measurement interval under stated conditions. Read More
- Failure reporting analysis and corrective action system (FRACAS)A closed-loop system of data collection, analysis, and dissemination to identify and correct failures of a product or process. FRACAS offers a process to track from identification to a suitable resolution of all problems, issues, or failures encountered. Read More
- Failure, secondaryA failure that produces operating conditions outside of design limits, thereby causing primary failure. Read More
- Failure substitutionIn maintenance, the use of a potential failure to preempt a functional failure; in design, the use of an item whose failure has minor consequences to preempt a failure that would have major consequences. Read More
- False alarmA fault indicated by BIT or other monitoring circuitry where no fault can be found or confirmed. Read More
- FatigueReduction in the failure resistance of a material over time as a result of repeated or cyclic applied loads. Read More
- Fatigue life1) For an item subject to fatigue, the total time to failure, e.g. crack initiation. 2) For a human, fatigue is weariness, exhaustion, or decreased attention related to labor, exertion, or stress. May also result from lack of sleep, circadian shifts, depression, boredom, or disease. May result(...) Read More
- FaultImmediate cause of failure (e.g., maladjustment, misalignment, defect, etc.). Read More
- Fault detection (FD)A process which discovers the existence of faults. Read More
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