MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.DOD-HDBK-791(AM)responsibility for integrated material inventory managementof a group of items.OOperating and support phase. The period in the systemlife cycle which starts with the delivery of the first itemof equipment to the using unit and terminates withdisposition of the system from the inventory.Operational readiness. The probability that, at any pointin time, a system or equipment is either operating satisfactorilyor ready to be placed in operation on demandwhen used under stated conditions, including statedallowable warning time. Thus, total calendar time is thebasis for computation of operational readiness.Operational testing. A series of tests conducted by thedesignated user to determine operational effectiveness,suitability, and military desirability of materiel and theadequacy of the organization, doctrine, and tacticsproposed for use.Operational value. A measure of maintainability whichincludes the combined effects of item design, quality,installation, environment, operation, maintenance, andand repair.Operating time. The time during which a system orequipment is operating in a manner acceptable to theoperator, although unsatisfactory operation (or failure)is sometimes the result of the judgment of themaintenance technician.Overhaul To restore an item to a completely serviceablecondition as prescribed by maintenance serviceabilitystandards.PPeriodic maintenance. Maintenance performed on equipmenton the basis of hours of operation or calendartime elapsed since last inspection.Physical interchangeability. A condition in which anytwo or more parts or units made to the same specificationcan be mounted, connected, and used effectively inthe same position in an assembly or system.Plan for logistic support. A major section of the materielacquisition plan that deals with all aspects of materielsupport planning.Preparation time. That element of active repair timerequired to obtain necessary test equipment and maintenancemanuals and to setup the necessary equipmentin preparation for fault location.Preventive maintenance. That maintenance performed toretain an item in satisfactory operational condition byproviding systematic inspection. detection, and preventionof incipient failures.Preventive maintenance time. That portion of calendartime used in accomplishing preventive maintenance. Itcomprises time spent in performance measurement;care of mechanical wear-out items; front panel adjustment,calibration, and alignment; cleaning; and scheduledreplacement of items.Probability of fault detection. By using authorized displays,manuals, checklists, test points, and test equipment,the probability that an existing fault—whichwould render a system or equipment inoperable (ormarginally effective) will be detected.Production model. An item in its final mechanical andelectrical form—of final production design made byproduction tools, jigs, fixtures, and methods.Production and deployment phase. The fourth phase inthe materiel life cycle. During this phase, all hardware,software, and trained personnel required to deploy anoperational system are acquired.Proportion of faults isolatable. Given that a fault hasoccurred which renders a system or equipment inoperable,the percentage of the faults that can be traced toan isolatable unit by using authorized displays. manuals,checklists, test points, and test equipment.Prototype model. A model suitable for complete evaluationof mechanical and electrical form, design, andperformance. It is in final mechanical and electricalform, uses approved parts. and is completely representativeof final equipment.QQualitative maintainability requirement. A maintainabilityrequirement expressed in qualitative terms—e.g.,niinimize complexity, design for a minimum number oftools and items of test equipment, and design for optimumaccessibility.Quantitative maintainability requirement. A maintainabilityrequirement expressed in quantitative termsi.e., a figure of merit in measurable units of time orresources required to accomplish a specific maintenancetask or group of tasks in relation to the applicableperformance requirements (reaction time. availabilities,downtime, repair time, turnaround time, etc.)RRandom failure. Any Failure whose exact time of occurrencecannot be predicted.G-8