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Mean time to repair (MTTR) is a basic measure of the maintainability of repairable items. It represents the average time required to repair a failed component or device. [1] Expressed mathematically, it is the total corrective maintenance time for failures divided by the total number of corrective maintenance actions for failures during a given ...
Mean time to recovery. Mean time to recovery (MTTR) [1][2][3] is the average time that a device will take to recover from any failure. Examples of such devices range from self-resetting fuses (where the MTTR would be very short, probably seconds), to whole systems which have to be repaired or replaced. The MTTR would usually be part of a ...
Mean time between failures (MTBF) describes the expected time between two failures for a repairable system. For example, three identical systems starting to function properly at time 0 are working until all of them fail. The first system fails after 100 hours, the second after 120 hours and the third after 130 hours.
Software reliability is the probability that software will work properly in a specified environment and for a given amount of time. Using the following formula, the probability of failure is calculated by testing a sample of all available input states. Mean Time Between Failure (MTBF)=Mean Time To Failure (MTTF)+ Mean Time To Repair (MTTR ...
If we are using equipment which has a mean time to failure (MTTF) of 81.5 years and mean time to repair (MTTR) of 1 hour: MTTF in hours = 81.5 × 365 × 24 = 713940 (This is a reliability parameter and often has a high level of uncertainty!) Inherent availability (Ai) = 713940 / (713940+1) = 713940 / 713941 = 99.999860%
Availability is the probability that a system will work as required when required during the period of a mission. The mission could be the 18-hour span of an aircraft flight. The mission period could also be the 3 to 15-month span of a military deployment. Availability includes non-operational periods associated with reliability, maintenance ...
where MTTR is the mean time to repair. The MTTF of a system is the sum of MTTF S and MTTF D. To understand the relationship between MTTF S and MTTF D consider the case of a switch that turns a motor on or off. The switch has two failure modes: the switch can fail stuck closed or the switch can fail stuck open.
The inclusion of delay times distinguishes mean down time from mean time to repair (MTTR), which includes only downtime specifically attributable to repairs. [1] Mean Down Time key factors: SYSTEM FAILURE. Identification & Recovery Time. First, the fact that the system is down must be identified, and maintainers notified & brought to action