Definition : MAINTENANCE

Maintainability:
The probability that a failed item will be restored to its satisfactory operational state
Maintenance:
All actions necessary for retaining an item or equipment in, or restoring it to, a specified condition
Reliability:
The probability that an item will perform its assigned mission satisfactorily for the stated time period when used according to the specified conditions
Availability:
The probability that an item is available for use when required
Mission time:
The time during which the item is carrying out its assigned mission
Downtime:
The total time during which the item is not in satisfactory operating state
Logistic time:
The portion of downtime occupied by the wait for a required part or tool
Failure:
The inability of an item to operate within the defined guidelines
Serviceability:
The degree of ease or difficulty with which an item can be restored to its working condition
Redundancy:
The existence of more than one means for accomplishing a stated function
Failure mode:
The abnormality of an item’s performance that causes the item to be considered to have failed
Human reliability:
The probability of accomplishing a task successfully by humans at any required stage in the system operation with a given minimum time limit (if the time requirement is stated)
Useful life:
The length of time a product operates within a tolerable level of failure rate
Maintenance concept:
A statement of the overall concept of the product specification or policy that controls the type of maintenance action to be taken for the product under consideration.
Corrective maintenance:
The repair or unscheduled maintenance to return items or equipment to a specified state, performed because maintenance personnel or others perceived deficiencies or failures
Continuous task:
A task that involves some kind of tracking activity (e.g., monitoring a changing situation)
Human performance:
A measure of human functions and actions under some specified conditions
Active redundancy:
A type of redundancy in which all redundant units are functioning simultaneously
Human error:
The failure to carry out a specified task (or the performance of a forbidden action) that could result in disruption of scheduled operations or damage to property or equipment
Active repair time:
The period of downtime when repair personnel are active to effect a repair
Inspection:
The qualitative observation of an item’s condition or performance
Overhaul:
A comprehensive inspection and restoration of a piece of equipment or an item to an acceptable level at a durability time or usage limit