- Email: [email protected]
R&M 2000. An Air Force Logistics Command challenge do it now
830
World Abstracts on Microelectronics and Reliability
A method to estimate the Weibull parameters for progressively censored tests. MARIO CACCIARI and GIAN CARLO MONTANARI. IEEE Trans. Reliab. R-36, 87 (1987). The paper treats a statistical method which allows estimation of Weibull parameters and their confidence limits for progressively-censored aging tests. Estimate of shape and scale parameters is based on a procedure which establishes a relation of the progressively-censored tests performed on a set of specimens with an equivalent singly-censored test, so that the Blom estimator can be used and the later failures of the aging test, which are pertinent to really-aged specimens. acquire a greater weight. Statistical confidence limits of timeto-failure percentiles are calculated by a method derived from Bain & Engelhardt. A statistical procedure is presented which makes it possible to obtain satisfactory estimates of the parameters and percentiles of a 2-parameter Weibull distribution, as well as of their confidence intervals, in the presence of life tests of the progressively-censored type. The comparison of the results for various samples, drawn from literature and statistically different as to the size, degree of censoring, material and aging conditions, exhibit the goodness of the proposed procedure. In particular, one notes an intrinsic characteristic of the method, that is, of weighting the later failures to a greater extend. Hence, the proposed method is useful in the statistical treatment of life tests, where moderately-large samples are often used and the later failures, those of really-aged specimens, are particularly important in order to characterize aging. Reliability of a consecutive-k-out-of-n:F system for Markov-dependent components. STAVROS PAPASTAVRIDISand MENELAOS LAMB1RIS. IEEE Trans. Reliab. R-36, 78 (1987). We examine a consecutive - k - out - of- n: F system, where the probability of failure of a component depends upon the state, (good or failed) of the preceding component; ie, the states of the components form a Markov chain. We compute the reliability of such a system, via a recurrence relation. Air force systems command approach to R&M. M. T. SMITH. IEEE Trans. Reliab. R-36, 291 (1987). This paper describes the approach to reliability and maintainability taken by the US Air Force Systems C o m m a n d in response to R&M 2000 initiative. Efective management, proper engineering, and new technology are discussed as the major elements of the approach. R&M 2000. An Air Force Logistics Command challenge do it now. RICHARD D. SMITH. IEEE Trans. Reliab. R-36, 299 (1987). This paper outlines the priorities of the Air Force Logistics C o m m a n d (AFLC) in supporting the R&M 2000 initiative; provides an overview of long, mid, and near-term R&M planning; and discusses initiatives within the A F L C depots and material management community. In view of decreasing manpower and funding AFLC is focusing on the basic elements of R&M with smart applications of developing technologies and innovative approaches within the Air Logistics Centers. A F L C has restructured itself to support such technologies at VHSIC, composites, and information. Several major offices and centers such as the Air Force Acquisition Center and the Air Force Coordinating Office for Logistics Research actively work R&M/supportability issues. These issues include R & M incentives, logistics support analysis, and advances in avionics leading to greater combat capability through R&M. On a more day-to-day basis the paper discusses R&M integration into the Weapon System Master Plan and ongoing efforts to enhance the R&M of existing systems. Initiatives have begun within depots to identify improvements in repair techniques which will lead to higher reliability and productivity. Within the material management community, new management approaches, use of ESS on repairable assets, and
enhancement of the product improvement process all highlight new efforts. R&M 2000: cutting the tether. IEEE Trans. Reliab. R-36, 281 (1987). This paper discusses the impact of the R&M 2000 initiative and its realizable potential for cutting the logistics tether which constrains the flexible employment of aerospace weapon systems. Four trends are identified which point to the necessity for changing the approach to designing systems for the modern battlefield. Within this context the paper outlines the R&M philosophy, followed by concrete examples which reinforce the thesis that industry can both develop and implement the technology necessary to provide a 21 ~t century combat capability. The myth that quality costs money is discussed with examples. The article concludes with a discussion of the enormous support infrastructure required for aircraft systems alone. The discussion points to the enormous reduction in men, materials, and facilities to be gained by smart engineering attention to reliability, maintainability, and quality within a system framework.
On the implications of R&M 2000 environmental stress screening. A. E. SAARI. IEEE Trans. Reliab. R-36, 342 (1987). The US Air Force R&M 2000 ESS policy differs little from that of the other armed services in that the same two primary screens, temperature cycling and random vibration, are employed at the module and end-item levels, Two of the screening parameters, 25 cycles and 30°C/minute, for module-level temperature-cycling exceed the norm. What is different is the requirement for part defect rates, 1000 parts per million (ppm) beginning in 1986 October and 100 ppm in 1989 October. Defense contractors will have to figure out how to work with their part suppliers, or develop in-house screening methods to get part defect rates down to 100 ppm. The Air Force has published a handbook and a companion guideline document for implementing the ESS policy. The handbook contains procedures for addressing the four problems: (1) estimating the fraction of defects entering the manufacturing process, (2) estimating the fraction of defects generated during manufacturing, (3) assessing the effectiveness of stress screens, and (4) determining an acceptable level of defects remaining on delivery. The ESS policy and guidelines can result in effective application of ESS and improved field reliability. US Army reliability initiatives--in concert with Air Force R&M 2000. S. J. LORBER. IEEE Trans. Reliab. R-36, 313 (1987). This paper describes how the US Army is improving readiness through enhanced reliability, availability, and maintainability (RAM). The Army is serious about supplying its personnel with the kind of equipment that stays on line. The US Army Materiel C o m m a n d is taking aggressive steps to ensure that systems achieve their RAM requirements. Too often the Army has been accused of settling for m i n i m u m performance. As is well known, industry is reactive; it responds to pressure to improve what the customer thinks is important. An important step to getting higher levels of reliability and maintainability is to stand together with the Air Force and Navy customers and demand the RAM design and manufacturing disciplines arc carried out and contractual RAM requirements are achieved. The achievement of requirements must be accomplished during system development and fielding. Improved RAM results in improved productivity, user satisfaction, and lower operating and support {O&S) costs. Linking R&M initiatives with O&S cost is an important step in justifying the up-front design and manufacturing disciplines that improve field performance. Meeting RAM requirements is the beginning and not the end of Army reliability efforts. Continued efforts to improve RAM are the thrust. For each system, the Army strives for continued improvement. Increased reliability reduces O&S
World Abstracts on Microelectronics and Reliability
A method to estimate the Weibull parameters for progressively censored tests. MARIO CACCIARI and GIAN CARLO MONTANARI. IEEE Trans. Reliab. R-36, 87 (1987). The paper treats a statistical method which allows estimation of Weibull parameters and their confidence limits for progressively-censored aging tests. Estimate of shape and scale parameters is based on a procedure which establishes a relation of the progressively-censored tests performed on a set of specimens with an equivalent singly-censored test, so that the Blom estimator can be used and the later failures of the aging test, which are pertinent to really-aged specimens. acquire a greater weight. Statistical confidence limits of timeto-failure percentiles are calculated by a method derived from Bain & Engelhardt. A statistical procedure is presented which makes it possible to obtain satisfactory estimates of the parameters and percentiles of a 2-parameter Weibull distribution, as well as of their confidence intervals, in the presence of life tests of the progressively-censored type. The comparison of the results for various samples, drawn from literature and statistically different as to the size, degree of censoring, material and aging conditions, exhibit the goodness of the proposed procedure. In particular, one notes an intrinsic characteristic of the method, that is, of weighting the later failures to a greater extend. Hence, the proposed method is useful in the statistical treatment of life tests, where moderately-large samples are often used and the later failures, those of really-aged specimens, are particularly important in order to characterize aging. Reliability of a consecutive-k-out-of-n:F system for Markov-dependent components. STAVROS PAPASTAVRIDISand MENELAOS LAMB1RIS. IEEE Trans. Reliab. R-36, 78 (1987). We examine a consecutive - k - out - of- n: F system, where the probability of failure of a component depends upon the state, (good or failed) of the preceding component; ie, the states of the components form a Markov chain. We compute the reliability of such a system, via a recurrence relation. Air force systems command approach to R&M. M. T. SMITH. IEEE Trans. Reliab. R-36, 291 (1987). This paper describes the approach to reliability and maintainability taken by the US Air Force Systems C o m m a n d in response to R&M 2000 initiative. Efective management, proper engineering, and new technology are discussed as the major elements of the approach. R&M 2000. An Air Force Logistics Command challenge do it now. RICHARD D. SMITH. IEEE Trans. Reliab. R-36, 299 (1987). This paper outlines the priorities of the Air Force Logistics C o m m a n d (AFLC) in supporting the R&M 2000 initiative; provides an overview of long, mid, and near-term R&M planning; and discusses initiatives within the A F L C depots and material management community. In view of decreasing manpower and funding AFLC is focusing on the basic elements of R&M with smart applications of developing technologies and innovative approaches within the Air Logistics Centers. A F L C has restructured itself to support such technologies at VHSIC, composites, and information. Several major offices and centers such as the Air Force Acquisition Center and the Air Force Coordinating Office for Logistics Research actively work R&M/supportability issues. These issues include R & M incentives, logistics support analysis, and advances in avionics leading to greater combat capability through R&M. On a more day-to-day basis the paper discusses R&M integration into the Weapon System Master Plan and ongoing efforts to enhance the R&M of existing systems. Initiatives have begun within depots to identify improvements in repair techniques which will lead to higher reliability and productivity. Within the material management community, new management approaches, use of ESS on repairable assets, and
enhancement of the product improvement process all highlight new efforts. R&M 2000: cutting the tether. IEEE Trans. Reliab. R-36, 281 (1987). This paper discusses the impact of the R&M 2000 initiative and its realizable potential for cutting the logistics tether which constrains the flexible employment of aerospace weapon systems. Four trends are identified which point to the necessity for changing the approach to designing systems for the modern battlefield. Within this context the paper outlines the R&M philosophy, followed by concrete examples which reinforce the thesis that industry can both develop and implement the technology necessary to provide a 21 ~t century combat capability. The myth that quality costs money is discussed with examples. The article concludes with a discussion of the enormous support infrastructure required for aircraft systems alone. The discussion points to the enormous reduction in men, materials, and facilities to be gained by smart engineering attention to reliability, maintainability, and quality within a system framework.
On the implications of R&M 2000 environmental stress screening. A. E. SAARI. IEEE Trans. Reliab. R-36, 342 (1987). The US Air Force R&M 2000 ESS policy differs little from that of the other armed services in that the same two primary screens, temperature cycling and random vibration, are employed at the module and end-item levels, Two of the screening parameters, 25 cycles and 30°C/minute, for module-level temperature-cycling exceed the norm. What is different is the requirement for part defect rates, 1000 parts per million (ppm) beginning in 1986 October and 100 ppm in 1989 October. Defense contractors will have to figure out how to work with their part suppliers, or develop in-house screening methods to get part defect rates down to 100 ppm. The Air Force has published a handbook and a companion guideline document for implementing the ESS policy. The handbook contains procedures for addressing the four problems: (1) estimating the fraction of defects entering the manufacturing process, (2) estimating the fraction of defects generated during manufacturing, (3) assessing the effectiveness of stress screens, and (4) determining an acceptable level of defects remaining on delivery. The ESS policy and guidelines can result in effective application of ESS and improved field reliability. US Army reliability initiatives--in concert with Air Force R&M 2000. S. J. LORBER. IEEE Trans. Reliab. R-36, 313 (1987). This paper describes how the US Army is improving readiness through enhanced reliability, availability, and maintainability (RAM). The Army is serious about supplying its personnel with the kind of equipment that stays on line. The US Army Materiel C o m m a n d is taking aggressive steps to ensure that systems achieve their RAM requirements. Too often the Army has been accused of settling for m i n i m u m performance. As is well known, industry is reactive; it responds to pressure to improve what the customer thinks is important. An important step to getting higher levels of reliability and maintainability is to stand together with the Air Force and Navy customers and demand the RAM design and manufacturing disciplines arc carried out and contractual RAM requirements are achieved. The achievement of requirements must be accomplished during system development and fielding. Improved RAM results in improved productivity, user satisfaction, and lower operating and support {O&S) costs. Linking R&M initiatives with O&S cost is an important step in justifying the up-front design and manufacturing disciplines that improve field performance. Meeting RAM requirements is the beginning and not the end of Army reliability efforts. Continued efforts to improve RAM are the thrust. For each system, the Army strives for continued improvement. Increased reliability reduces O&S