Service life is a product’s expected lifetime. This period of time can be increased through corrective and preventive maintenance, or other “refresh cycles.” Service life is sometimes confused with mean time between failure (MTBF), or the life associated with a particular item in a system; however, it is primarily related to a business policy regarding whether or not a manufacturer will continued to provide support and upgrades. Continue reading
System effectiveness is a measure of the ability of a system to achieve a set of specific mission requirements.
- System effectiveness is a function of:
Time is of fundamental importance in the quantification of the basic terms which were defined in other definitions found in this blog, for it is this factor which permits the attributes to be measured rather than described in merely qualitative terms. The usual measures of time – the year, the month, the day, and the hour form the basis for the computation of reliability. Where appropriate, the time concepts may be replaced by distance, cycles, operations or other quantities.
The intrinsic availability of a system or equipment is the probability that it is operating satisfactorily at any point in time when used under stated conditions, where the time considered is operating time and active repair time.
Thus, intrinsic availability excludes from consideration all free time, storage time, administrative time, and logistic time. As the name indicates, intrinsic availability refers primarily to the built-in capability of the system or equipment to operate satisfactorily under stated conditions.
Serviceability is the ease or difficulty with which an equipment can be repaired
Intuitively, it would seem that some term should be used to represent the degree of ease or difficulty with which an equipment can be repaired. The term “serviceability” has been selected for this concept. Serviceability has a strong influence on repairability, but the two are essentially different concepts. Serviceability is an equipment design characteristic,
while repairability is a probability involving certain categories of time.
Maintainability is defined as 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, at each prescribed level of maintenance and repair.
Repairability is defined as the probability that a failed system will be restored to operable condition in a specified active repair time.
System design adequacy is the probability that a system will successfully accomplish its mission, given that the system is operating within design specifications.