Reliability - property of an object to keep in time within the established values of the parameters characterizing the ability to perform the required functions in the set modes and conditions of use, maintenance, storage and transport .
Intuitively, the reliability of objects associated with the failures of inadmissibility. It is the understanding of grade in the "narrow" sense - object property to maintain a usable state for a certain time or a certain operating time. In other words, the reliability of the object lies in the absence of unforeseen harmful changes its quality in service and storage. Reliability is closely related to the various parties operating process. Reliability in the "broad" sense - comprehensive property, which depending on the target object and its operating conditions can include properties of reliability, durability, maintainability and retentivity as well as a certain combination of these properties.
Maintainability - object property, adaptability to maintain and restore a healthy state by maintenance and repair.
A system allowing repair in the course of its operation, called recoverable. Some systems in fulfilling their functions for reasons of technical or economic conducting repairs not allowed. An example of a non-recoverable for technical reasons, the system is. For economic reasons, not reproducible, such as ball bearings, since by virtue of their production processability new product is significantly less repair and replacement set of mechanical working operations. There are products such as aircraft tires or vanes of gas turbine engines, recovery of which is technically and economically feasible, but is forbidden safety regulations.