MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.DOD-HDBK-791(AM)CHAPTER 9HUMAN FACTORSThe concept of human factors and the relationship between human factors and maintainability arediscussed. This includes consideration of body measurements in designing for maintainability, with a goal ofdesigning equipment for use by at least 90% of the user population (male and female). The major human sensesand the relationship of each to maintainability design are also presented, as is the need to consider thepsychology, motivation, and training of personnel. Other topics included are human error, stress, andstrength.9-1 INTRODUCTIONIn order for equipment to be used most efficiently, itmust be designed for the specific user population. Thisconstraint upon design is obviously, although perhapsunconsciously, one of the designer’s primary considerations.Designers must design for personnel who, in tacticalsituations, will be under conditions of stress andfatigue from many causes. A performance decrement mayarise in the tactical situation not so much because troopsare basically unable to perform but because the individualsoldier is overloaded both physically and mentally.Accordingly, equipment must be designed so that theprocedures for using and maintaining it are as simple aspossible. Equipment should not require intellectual tasksthat will detract from the user’s primary mission.Machines work well only if the personnel operating themperform their tasks satisfactorily. Therefore, the systemengineering concept must be one of a person/machinesystem, i.e., a system in which operator and machineinteract efficiently to perform a function. Training canimprove operator or crew proficiency; however, trainingshould not be considered a substitute for good design.Human factors engineering is the science of applyingtechnical knowledge to the design of equipment toachieve effective person machine integration, operation,and ease of maintenance. Human factors also are anessential element of the Manpower and Personnel Integration(MANPRINT) program, whose purpose is toimpose human factors, manpower, personnel, training,system safety, and health hazard assessment considerationsacross the entire materiel acquisition process. Thesaying, “People are our most important resource”, hasbeen uttered many times. ‘The application of human factorsengineering offers the prospect of moving beyondrhetoric and into action.The human factors engineer relates human factors suchas size, strength, and human sensory perceptions to thetask to be accomplished. Failure to consider these factorsresults in increased problems of operability and maintainability.To avoid these problems, human factors engineersconsider complex military systems as person/ machinesystems, including the capabilities and limitationsof personnel under various conditions. Specifically, humanfactors engineering is concerned with1. Persons, their characteristics—biomedical andpsychological and their capabilities2. Persons and their environment3. Persons as an integral component of the system4. Person/machine interfaces.Because maintenance economy and efficiency are significantlyaffected by how well the human factors engineeringfunction is implemented, the human factors engineer isresponsible for insuring that an optimum interface existsbetween human capabilities and materiel design features.Each of the AMC commands have human factorsengineers—representatives of the Human EngineeringLaboratory—assigned to assist them in this importantarea.Important sources of information to guide the maintainabilityengineer in assuring that human factors engineeringis integrated into the design process follow:1. MIL-H-468S5 (Ref. 1). Establishes human engineeringprinciples and procedures for acquiring anddeveloping military systems and equipment. This militaryspecification integrates personnel into the design andprovides the Army with management control of the contractor’seffort. For major acquisition programs this isusually accomplished with a Human Engineering ProgramPlan.2. MIL-STD-1472 (Ref. 2). Applicable to the designof all military systems and equipment. Ref. 2 includeshuman engineering design requirements for maintainability,labeling, work space design, and displays; and humanengineering criteria, principles, and practices necessary toachieve mission success through the integration of thehuman into the system and to achieve effectiveness, simplicity,reliability, and safety of operation.3. MIL-HDBK-759 (Ref. 3). Establishes, in handbookform, general data and detailed criteria for humanfactors engineering application in the design and developmentof Army materiel for ease of maintenance. Areascovered in Ref. 3 of particular interest area. Anthropometric data for men and womenb. Features relating to military hardware—e.g.,ammunition, missiles, tank gun control systems, andoptical instrumentsc. Effects of environmental factors on humanperformanced. Physical limitations of the human body—strength and movemente. Illumination requirements.Anthropometric data, body strength and movement9-1