Designing the CF-18 to be operationally ready

Primary Hornet program requirements include improved Operational Readiness (OR) and reduced Life Cycle Cost (LCC) compared to previous tactical aircraft. These requirements were translated into definitive and challenging reliability (R) and maintainability (M) design requirements. This paper describes the design and management techniques used to design superior R and M characteristics into the CF-18. A key to the Hornet's improved Operational Readiness is the firm R and M guarantees which will be demonstrated during the development program. Another important program management feature is the substantial R, M, LCC, and program management incentives (totalling $39M) which the contractor can earn. Principal CF-18 features designed to provide improved reliability include avionics equipment derating, improved cooling of the avionics, and reduced parts in the major subsystems such as radar, engine, and crew station. The Hornet's F404 engine also is designed for simplicity and reliability, being about four times as reliable as the J79. A major factor in achieving this improved CF-18 reliability is designing and testing to a realistic operational mission environment (OME). Most Hornet subsystems were required to complete reliability development testing utilizing this simulated OME. Maintainability features of the CF-18 design include improved equipment access, extensive built-in-test (BIT) and fault isolation, and an auxiliary power unit (APU) for ground maintenance. The Hornet's R and M performance during the flight test program demonstrates that the challenging reliability and maintainability design requirements are being met and often exceeded. The paper concludes with a summary of lessons learned during the Hornet program.     

ALE?A Carrier Aircraft Availability Model

The Avionics Logistics Effects (ALE) model was developed in 1973 in response to a US Navy requirement to evaluate potential benefits of reliability and maintainability improvements that might be incorporated into the AWG-9 weapon control system on the F-14 aircraft and AWM-23 ground support equipment. The model simulates the entire F-14 aircraft (avionics and non-avionics) in terms of squadron flight operations, maintenance, and support aboard an aircraft carrier. Its major application is to determine the impact of avionics system design and maintenance changes on aircraft availability. Several studies have been performed with the ALE model, and one in particular is discussed in this paper. In this case, Hughes recommended 27 separate reliability and maintainability improvements to the AWG-9/AWM-23 systems. The contribution of these improvements to F-14 availability is discussed, with particular emphasis on achieved crisis-flight rate.     

Current Management Reliability Objectives

In summary, I will keynote this Symposium by expressing the following six points: 1) We accept the view which has been expressed by General Davis and others that reliability is a general management responsibility. 2) To enable general management to do their part effectively, reliability specialists must express their requests for support in terms of cost effectiveness. 3) Reliability is a branch of engineering technology that, like all other branches, must be supported by a research program. 4) After research has provided potentially effective reliability technology, the Program Plan for each project must be such as to ensure effective use of this technology. 5) A system of operations evaluation must be established to give immediate visibility to any deficiencies in compliance with or the results of reliability plans. 6) Our experience has shown the traditional practices of the aerospace industry are well suited to achieving reliability. It is important for customer contracting agencies to recognize that many of the practices which enable industry to create reliability have to be supported by overhead funds. Almost the entire Reliability Resources Development Program must be absorbed by our overhead budget. Also, it is important for these contracting agencies to recognize that reliability resources must be an important factor in ``Make' or ``Buy' decisions. For example, the Prime Contractor's resources include design assurance and quality assurance disciplines which may be lost when an item is transferred from the ``Make' to the ``Buy' category.     

Guidelines for integrating RAM considerations into an engineeringproject

Reliability, availability and maintainability (RAM) program guidelines developed by the US Department of Energy RAM working group are presented. These guidelines present a structured RAM process for integrating RAM considerations in each of six defined project phases: (1) feasibility study, (2) conceptual and preliminary design, (3) detailed design, (4) procurement, (5) startup, and (6) operations. This structured RAM process is described using a flowchart identifying the primary tasks and decisions within the process. A RAM program, based on these guidelines, applies this structured RAM process in each project phase. The activities required to perform the tasks in the RAM process and the tools that can be used in those tasks are discussed. A matrix shows the specific activities and associated tools that are generally most useful for performing a particular task during a particular project phase. The guidelines apply to any engineered system and provide a structured approach for designing and implementing an effective RAM program throughout a project     

Commercial-Components Initiative: Ground Benign Systems-plasticencapsulated microcircuits

The purpose of the Commercial Components Initiative-Ground Benign Systems was to determine if commercial off-the-shelf PEM (plastic-encapsulated microcircuits) are suitable for use in ground-benign, dynamically-fixed military electronic systems. If so, they could replace the more expensive components presently specified by DoD (US Dept. of Defense), resulting in appreciable life-cycle cost savings. At issue is whether the components produced for the commercial industry are reliable and durable enough to withstand the environments and life expectancies of military systems. Reliability was not formally proven. A more practical informal reliability test for this project, which DSD dubbed Run for Reliability, was to install the PCB in the system and let the operational hours accrue beyond the subsystem and Signal Processor lifetime allocations. The Run for Reliability shows promise that commercial hardware could be proven in a formal reliability demonstration test     

CALCE/RAMCAD for Electronics

The University of Maryland's Computer Aided Life Cycle Engineering (CALCE) research effort is aimed at developing techniques for design, analysis, prediction, and optimization of electronics with respect to a variety of design goals. Performance, producibility, reliability, maintainability, life-cycle cost, safety, etc., are the design criteria which are being integrated through the application of interactive heuristic and algorithmic design optimization techniques. The University of Maryland Reliability and Maintainability Computer-Aided Design (RAMCAD) research is CALCE and is focused on second- and third-level electronic package design with respect to interfacing thermal, mechanical, and reliability analysis. The goal is to make reliability and maintainability an integral, real-time, and upfront part of the design process, such that the need to resubmit designs will be eliminated. The motivation behind this project was the fact that schedule constraints are often compromising the effectiveness and efficiency of the design process. To achieve the goal of CALCE/RAMCAD, a cohesive and extensible design environment for analysis and tradeoff tools was developed. A system executive controller that integrates tools for analysis while providing system transparency, design data management, and process management was developed to guide the user through the design process and provide direct access to the design tools. These developments required the integration of computer-aided design (CAD), artificial intelligence (AI), and decision support (DS) techniques. Attention to human factors and the use of interactive graphics were also instrumental in the development.     

A data base management (DBMP) program for integrated logistics support (ILS)

The Integrated Logistics Support function and its interdependent disciplines such as life cycle costing, reliability and maintainability engineering, spares determination and sparing philosophies is discussed in this paper. This inter-relationship is pursued from a Data Base Management Program (DBMP) viewpoint. The (DBMP) can be applied directly to the optimum design and selection of a system of equipment for a sailing vessel, an aircraft, a computer complex or a large orbiting space station.     

R&M Implications of the DoD Acquisition Improvement Program

The US Dept. of Defense (DoD) Acquisition Improvement Program (DAIP) specifically considers the reliability and maintainability of weapon and command & control systems, and thus has significant R&M implications. Its comprehensiveness naturally introduces conflicting objectives. Implementation guidance offered in connection with specific management and system design principles adds further complications. Key DoD policymakers are not unanimous in their support of DAIP specifics nor are the separate Services. Furthermore, change is never easy, especially when institutional inertia as great as that found in DoD is involved. After studying the program directives, instructions, and guidelines, my conclusions and recommendations are as follows. 1. The objective is to require the Services to develop acquisition strategies for system acquisitions. 2. The specifics of the strategies and the processes are designed to enhance readiness, reduce costs, shorten acquisition time, and stabilize the procurement system. 3. Acquisition strategies encompass the entire process for the system, preplanned product improvement, and post-production support. 4. Approaches to these process improvements are still being worked out and therefore in a state of transition. 5. R&M (reliability & maintainability) aspects have neither received sufficient implementation attention nor has their interrelationship with the other program provisions been adequately assessed. 6. Preplanned product (P3I) improvement introduces a new wrinkle into R&M activities. Traditional program tasks will need to be applied, consistent with the incremental, technology insertion philosophy of this acquisition improvement initiative. 7. R&M growth must become an element of P3I in the approved acquisition strategy.     

Engineering Reliability Management

This paper describes various areas of the reliability management. Areas covered are the historical development, general management considerations, achieving the reliability program objectives and guidelines for the reliability program management, reliability and maintainability management tasks in the product life cycle, steps to improve reliability of engineering products, reliability and maintainability departments, reliability manpower, documents and tools for reliability management, reliability auditing and pitfalls in reliability program management.     

基于桥联模型的高可靠计算机设计

机载计算机的任务可靠性对飞机飞行安全至关重要,而提高任务可靠性的一个有效途径就是进行余度设计。文章从研究两种常用的双余度容错模型出发,将桥联模型应用于机载计算机的双余度设计。通过对工作模型的故障容错机制的分析,证明该双余度设计可有效提高机载计算机的任务可靠性,具备一定的工程实用价值。     

Queuing Models for Estimating Aircraft Fleet Availability

The availability of a small fleet of aircraft in a flying-base, repair-depot combination is modeled and studied. First, a deterministic flow model relates parameters of interest and represents the state-of-the art in the planning of such systems. Second, a cyclic queue model shows the effect of the principal uncertainties in operation and repair and shows the consequent decrease in the availability of aircraft at the flying-base. Several options such as increasing fleet size, investments in additional repair facilities, or building reliability and maintainability into the individual aircraft during its life-cycle are open for increasing the availability. A life-cycle cost criterion brings out some of these features. Numerical results confirm Rose's prediction that there exists a minimal cost combination of end products and repair-depot capability to achieve a prescribed operational availability.     

军用电子设备的可靠性管理

可靠性管理同可靠性设计一样,是设备可靠性工作的重要内容。阐述了可靠性管理的 概念及特点,分析了设备寿命周期各阶段可靠性管理的主要内容,包括论证阶段、方案阶段 、工程研制阶段、定型阶段、生产阶段、使用阶段等,讨论了设备可靠性保证大纲的拟制依 据、内容以及评审要点。最后指出,可靠性管理虽然繁琐,只要按有关国军标的要求,科学 制定并严格执行可靠性保证大纲,就可以做好设备的可靠性管理工作,从而确保设备的可靠 性。     

Aircraft interface with the future ATC system

The authors outline how the advantages of improved navigational accuracy can benefit both the individual aircraft and the air transportation system despite a mixed environment. The development of advanced navigation, flight planning, performance optimization, automatic guidance, and other capabilities in current and future flight management systems, together with the availability of digital communications between the airplane and ATC, suggests the need to review the potential airplane contributions to the ATC system of the future. A number of application areas utilizing current airborne flight management technology have been proposed for use with ATC that could provide significant operational benefits. These include: time-navigation applications in traffic management; multisensor navigation to provide automatic dependent surveillance; improved precision for approach, missed approach, and departure procedures; and improved navigational accuracy supporting reduced airway widths, holding pattern airspace, and aircraft separation standards. Several examples of operational benefits for operators and ATC during the transition period are identified, and the need for integrating these features into future ATC capabilities and procedures is stressed     

Shuttle orbit flight control design lessons: Direction for space station

The Space Shuttle orbit flight control system, which operates during all exo-atmospheric flight phases, has successfully met operational requirements. Many design integration and operational issues that required resolution during development and testing provide an experience base that will benefit the development of future space systems, particularly the Space Station. To this end, the applicable Shuttle and Space Station hardware/software is reviewed with some perspective provided on how current design groundrules were derived and how issues that affected the Shuttle orbit control system design are a pathway for the Space Station. Some of the most significant lessons learned from the Shuttle are summarized, with a discussion of the effect of performance and design of hardware, including the data processing system, on software structures and usage procedures. Crew interface issues and important results from man-in-the-loop tests are summarized. Problems resulting from trying to meet difficult orbital operational objectives, including some sophisticated payload operations are characterized. Several proposed Shuttle flight control design improvements, developed in response to some of the lessons learned so far, are identified. Potential application of the Shuttle design lessons and new control technologies to the Space Station are discussed.     

Fault-tree analysis: a knowledge-engineering approach

This paper deals with the application of knowledge engineering and a methodology for the assessment and measurement of reliability, availability, maintainability, and safety of industrial systems using fault-tree representation. Object oriented structures, production rules representing the expert's heuristics, algorithms, and database structures are the basic elements of the system. The blackboard architecture of the system supports qualitative and quantitative evaluation of the fault tree. A fuzzy set approach analyzes problems with few failure data or much fuzziness or imprecision. Fault-tree analysis is a knowledge acquisition structure that has been extensively explored by knowledge engineers. Reliability engineers can apply the techniques developed by this area of computer science to: (1) improve the data acquisition process; (2) explore the benefits of object oriented expert systems for reliability applications; (3) integrate the several sources of knowledge into a unique system; (4) explore the approximate reasoning to handle uncertainty; and (5) develop hybrid solution strategies combining expert heuristics, conventional procedures, and available failure data     

Helios prototype flying program hits problems

The Helios prototype solar-electric flying wing has suffered problems during a check-out flight at the US Navy’s Pacific Missile Range Facility (PMRF). Aloft for about 15 h at altitudes up to 52 000 feet (16 km), engineers checked out modifications and upgrades made to the aircraft over the past two years.This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news     

可靠性工程管理的进展

总结了目前可靠性工程管理的现状，探讨了问题的症结之所在；探索了可靠性工程管理的先进方法和措施，提出了细化可靠性、维修性、测试性和保障性的设计要求，规范相应的设计技术文件，确保可靠性、维修性、测试性、保障性的要求在设计开发阶段的贯彻落实的可靠性工程管理方法。     

Reliability analysis of systems with operation-time management

This paper considers the reliability analysis of systems whose operation time is managed with regard to criticality of faults. Several analysis approaches are proposed for the numerical probability analysis of one such operational scenario: FOTM (flight operation time management). The equations derived for the Markov chain based method are novel and their implementation in the tool SPNP (Stochastic Petri Net Program) could help in assessing the risk reduction due to FOTM. The analysis methods are quite general and can be applied to other similar situations where system-failure risk is decreased by operation-time management     

Maintenance Techniques in Distributed Communications Switching Systems

The reliability and maintainability design criteria that were a part of large central-control communication systems, have been combined to produce deferred maintenance concepts in fully distributed communication systems. Combining these concepts allows the achievement of a cost-effective life-cycle design for communication switching systems. In a hardware/software environment one should not separate hardware maintainability and software maintainability, nor separate the reliability and maintainability of the system. Reliability models are being developed that reflect a constant rate for transient faults and a decreasing rate for catastrophic faults. The relationship of software bugs to their number and type of manifestation is being defined. Designs for primarily non-attended system sites should include appropriate maintenance concepts in order to be cost effective. If two or more individual repairs can be made with each maintenance visit to a site, the total area maintenance staff can be reduced. Implementation of deferred maintenance techniques can raise the availability level of the services provided, especially for a distributed communication switching system. Several examples of practical techniques for developing deferred maintenance concepts are presented, and topics such as the manning versus non-manning of sites, the time of day effects on state diagrams, centralized maintenance, and computer modeling techniques are discussed. The current and potential maintainability concepts and analysis tools that are discussed in this paper can be used to develop cost-effective maintenance concepts as distributed systems become more prevalent.