MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.ConsiderationPERSONNELMan-Hours (active maintenance)Man-YearsManpower Utilization (average)TRAININGNumber of Military Occupational Specialty (MOS)Types InvolvedTraining Cost per MOSTotal Training CostTOOLS AND TEST EQUIPMENTSpecial Tools, Kits, Test EquipmentREPAIR PARTSNumber of Federal Stock Numbers (FSNS) InvolvedUnitNo. of Type Items StockedQuantity of Items UsedIntermediateNo. of Type Items StockedQuantity of Items UsedAVAILABILITYActive Maintenance DowntimeInactive Maintenance DowntimeStandardVehicle86804.34(Undetermined)3$ 5626.00(2 types)$22,504.00$2143.421260(Unknown)1130(Unknown)2350833547,510 (est)(per fleet per year)DOD-HDBK-791(AM)ModularVehicle62273.11312.5%1000277 (est)28 (est)1088249 (est)2265625720,223(per fleet per year)Figure 5-7. Data Output Balance Sheet5-6.4.1 Feed and Eject ModuleCHAIN GUNS are externally powered guns, inwhich the ammunition feed is powered by an electricmotor rather than by gas from a fired projectile (Ref. 8).Fig. 5-8 shows the bolt assembly and drive train moduleswithin the CHAIN GUN. Failure in any of the parts of thechain drive module requires only removal and replacementof the module.5-6.4.2 Complete Gun ModularizationFig. 5-9 shows the assembled 5.56-mm M231 SubmachineGun. Its modularization has resulted in simplification,reduced weight, improved maintainability, andpotentially decreased production costs. Fig. 5-10 illustratesthe modular assemblies. The barrel assembly isdesigned for quick change. These five modular units—except for removal of the barrel from the upper assemblycannotbe reduced further to the usual array of unmanageablepiece parts associated with earlier submachinegun models. The weapon can be disassembled in approximately10s without special tools. Compared to previouslyfielded standard submachine guns, the five modular cornponentsrepresent a major reduction in parts.5-6.5 HELICOPTER ENGINEThe complete Lycoming T-53 gas turbine engine is builtof many subassemblies that can be exchanged as completemodules (Ref. 9). In case of extensive damage within onesubassembly, the engine can be made operable again in ashort time by exchanging an entire module. Also it ispossible to replace the combustor assembly, the mainreduction gear, the fuel control, and other accessorymodules. The axial compressor housing is split lengthwiseso that compressor vanes or blades can be replaced.The design of the T-53 permits removal of the entirecombustor assembly, which contains the power turbinewithin the exhaust diffuser, by simply unbolting at thecombustion chamber flange—an operation accomplishedwithout removing the engine from its mounting in theairframe. In this way all hot end parts—turbine blades,5-13