MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.DOD-HDBK-791(AM)Support equipment. Items necessary for the maintenanceor operation of the system which are not physically partof the system.Support parameter. Any of the several categories of supportresources—such as personnel, repair parts, andfacilities—required to support materiel.System effectiveness. The probability that a system canmeet successfully an operational demand within a giventime when operated under specified conditions.System engineering. The application of scientific andengineering knowledge to the planning, design, construction,and evaluation of man/machine systems andcomponents. It includes the overall consideration ofpossible methods for accomplishing a desired result,determination of technical specification, identificationand solution of interfaces among parts of the system,development of coordinated test programs, assessmentof data, integrated logistic support planning, andsupervision of design work.TTestability. A design characteristic that allows the statusof a unit or system to be determined in a timely andcost-effective manner.Testability analysis. An element in equipment designanalysis effort related to developing a diagnostic approachand then implementing that approach.Test and checkout level. The functional level at whichequipment status is verified.Test, measurement, and diagnostic equipment (TMDE).Any system or device used to evaluate the operationalcondition of materiel to identify and/or isolate anyactual or potential malfunction.Test point. A convenient and safe access to functionalportions of materiel that is to be used so that a significantquantity can be measured or an access introducedto facilitate maintenance, repair, calibration, alignment,or monitoring.Total downtime. That portion of calendar time duringwhich a system is not in condition to perform itsintended function. It includes active maintenance (preventiveand corrective), supply downtime due to unavailabilityof needed items, and waiting and administrativetime.Total technician time. The total man-hour expenditurerequired to complete a maintenance task. It includesactive technician time and delay technician time.Trade-off. A comparison of two or more ways of doingsomething in order to make a decision. Decision criterianormally are quantitative.Troubleshooting. Locating and diagnosing malfunctionsor breakdowns in equipment by means of systematicchecking or analysis:uUnitization. The process of providing a series of plug-inunits or similar subassemblies. each of which containsall parts necessary to make up a complete functioningcircuit or stage. Each circuit or stage can be independentlyremoved and replaced with a like unit or subassembly.See also module.Unit maintenance. A category of maintenance which iscategorized by quick turnaround based on repair byreplacement and minor repair -e. g., adjust, clean, lubricate,tighten. The maintenance is performed by theoperator, crew, and company or battalion maintenancepersonnel.Unscheduled maintenance. All maintenance work notspecifically planned to occur at a prearranged time.Useful life. The total operating time in which an itemremains operationally effective and economically usefulbefore wear-out.vValidation phase. The second phase in the materiel acquisitionprocess. This phase consists of those steps necessaryto resolve or minimize special logistic problemsidentified during the conceptual phase. verify preliminarydesign and engineering, accomplish necessaryplanning, fully analyze trade-off proposals. and preparecontracts as required for full-scale development.Value engineering (VE). An organized effort directed atanalyzing the function of an item with the purpose ofachieving the function at the lowest overall cost.wWear-out. The point at which further operation isuneconomical.Wear-out failure. A failure that occurs as a result ofdeterioration or mechanical wear and whose probabilityof occurrence increases with time. Wear-out failuresgenerally occur near the end of the life of an item andare usually characterized by chemical or mechanicalchanges. These failures frequently can be prevented byadopting an appropriate replacement policy based onthe known wear-out characteristics of the item.G-10