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The author discusses various facets of All Weather Operations for V/STOL type aircraft, including the environmental requirements. Progress on the military developments of the Marine Corps, Air Force, and Army are reported. Development of components for the IHAS program and various environmental test programs are described.

This paper presents an analysis of major life-limiting problems in military and commercial service experience. Design action and means to verify the solution have included engine and laboratory tests. The experience gained has led to the development of design criteria, most of which have a basis in analysis of flow models, rotor dynamics, wave mechanics, heat transfer, or stress fields. Design criteria, when adequately substantiated, become effective means of helping protect new designs from life-limiting problems possibly related to: coking of vent tubes, seals, and sump walls; materials joining; low-cycle fatigue, including thermal cyclic stresses; fretting and wear; bearing retention; blading; installation effects; and flexural vibration and fatigue of the thin walls of flow passages.

Review and extension of results from an EIA Reliability (G-41) Committee Task to determine factors degrading reliability in the use phase provide a basis for design improvements. A matrix of potential degradation factors and measures of significance are used in development of analysis methods to determine optimum correction modes in terms of cost and time. Recommendations include a realistic downtime model and considerations for design analysis to aid in improving use reliability.

Two Air Force programs are currently under development for the collection, reduction, storage, analysis and dissemination of reliability, maintainability and other system effectiveness parameter experience data. The System Experience Correlation and Analysis Program, being developed by the Ballistic System Division, will provide the means for measuring and monitoring weapon system effectiveness, flagging critical problems, reducing data analysis costs, providing information for tradeoff analysis and an experience retention capability that will enable comparison of weapon systems. The Reliability Analysis Central, being developed by Rome Air Development Center, will be a centralized Air Force clearinghouse for part and device reliability information and experience and will serve as a ready source of current cumulative reliability knowledge for the engineering and logistic activities of the Air Force and their contractors.

THE PAPER WILL present the background of Apollo Applications Program objectives, moving from 28 day missions to 56 days, to 120 days, etc., up to one year. It will discuss the concept of revisitation and reuse of hardware left in orbit and the recognition of the need for in-flight maintenance for enhancing probability of mission success. The design of the airlock module and multiple docking adapter which is aimed towards ease of module replacement, will be presented. The orbital workshop, planned for a late 1968/early 1969 launch, has a programmed set of experiments in the maintenance area, which will try to provide a baseline of astronaut capability in the maintenance area. These experiments will be discussed in detail.

Perhaps the most important system requirement for future unmanned space programs like Voyager is First Try Success. Responsibility for meeting this requirement will rest on both the Government and Industry, each of whom must be completely realistic in their approach to the program. General Electric has conducted systematic studies of spacecraft failures and has reached some quite unexpected conclusions concerning them. The management of past spacecraft programs has contributed to the failures which have occurred. Achievement of long life and first try success requires a fresh look at management philosophy, but short cuts to success do not appear to be available.

Managers of complex human factors efforts have the problem of managing their management information. This requires tools for monitoring and assuring both the flow and application of current information to the solutions of technical problems. The challenge posed by the amount and diversity of both information and requirements for information has outstripped the capacity of current methods for handling and managing such information. Some core problems involve lack of between-persons agreement regarding the judgment, evaluation, and characterization of information. There is evidence that behavior-oriented experimental research of the human factors variety can help to solve such core problems. Three examples of such empirical study projects are described.

The nature and magnitude of differences between intrinsic and operational reliability and maintainability characteristics are presented. Relative supplier and user responsibility is cited. The difficulty is justifying increased reliability and maintainability is illustrated by means of hypothetical equipment selection and direct mutual dependence of reliability and maintainability is demonstrated. A suggested approach to the reconciliation of intrinsic and operational values consists on recognition of mutual responsibilities of supplier and user, development of a clear conditional frame of reference for intrinsic claims, user, development of a clear conditional frame of reference for intrinsic claims, and application of more effective operational management controls. Data bank requirements for this approach are also established.

Chrysler's Quality Data Reporting System is primarily designed to collect information on quality defects reported by line inspectors and report them to the production areas so that corrective action may be taken. Individual input machines throughout the production areas feed data to the computer for processing and reporting. Along with this “Production Oriented” approach to Quality Reporting are the built in Quality Control tools for the analysis, summarization and management type reporting of quality conditions that allows plant management to stay in touch with quality at all times.

This paper describes PRINCE/APIC - a parts and materials information center which utilizes a blend of mechanical and electronic methods of data storage and retrieval. The information center was originally organized as PRINCE (Parts Reliability INformation CEnter) in the early sixties to serve the parts information exchange needs of MSFC's Saturn Parts. Program. In February of 1965 a direction was issued designating PRINCE as the information center for NASA's Apollo Program (Apollo Parts Information Center); hence the name, PRINCE/APIC. The operations of PRINCE/APIC's Data Input Section, which performs all of its data acquisition and storage functions, and the Inquiry Service, which retrieves and disseminates this data, are described in detail. PRINCE/APIC's storage files and the types of information it has available for the users are discussed. Also presented in this paper are some PRINCE/APIC usage factors.

This paper presents a Navy (Special Projects Office) method of integrating all reliability data obtained from testing, inspection, and trouble and failure reporting by means of an Integrated Data Plan. The System is fully documented in NAVWEPS OD 29304 “Guide Manual for Reliability Measurement Program” as a derivative of a requirement contained in Military Specification MIL-Q-21549B of 10 June 1963, entitled “Product Quality Program Requirements for Fleet Ballistic Missile Weapon System Contractors.” Because one of the data inputs to this System is from trouble and failure reports, this paper presents the Special Projects Office Trouble and Failure Report (TFR) Program (which is less well known outside of the Navy) for the Fleet Ballistic Missile Weapon System to illustrate how data is utilized to enhance the quality/reliability/maintainability of a weapon system.

This paper contains a discussion of the maintainability technology and controls developed and implemented during early design of the F-111 to ensure the achievement of desirable maintainability goals. The validity of the approach, which entails determination and prediction of maintainability parameters, is verified by actual examples. The major maintainability design decisions applicable to the program are also discussed briefly.

The use of entropy concepts in determining the reliability of a given measurement is presented in this paper. In particular, the problem of the analysis and report of given data with respect to some quotation of the degree of confidence is considered. Properties of probabilistic entropy are introduced and its application is demonstrated by means of an example. An entropy of a given one-dimensional Gaussian distribution is discussed. Methods presented are general enough so that the same ideas can be extended to other types of distribution.

This paper considers a system whose components, upon failure, are repaired or replaced. Only two system states, the “operating” state and the “failed” state are distinguished. The time to failure and the time to repair of the system are assumed to be random variables with general distribution functions. A criterion of system worth is the random variable “excess time,” denoted by B(t), and defined as the total time the system is down for t units of time spent in the operating state. The following questions are answered in this paper: (a) What is the distribution function of B(t)? (b) What are the moments of B(t)? (c) What is the asymptotic behavior of B(t) for large t? (d) How can one make approximate probability statements about B(t)? It is shown that the gamma distribution is a suitable approximation for the conditional distribution of B(t), given that at least one failure has occurred, and that for t greater than 20 mean failure times the distribution of B(t) is practically normal.

This paper describes a statistical method for estimating and demonstrating the reliability of clustered liquid rocket engines from development, qualification, production, acceptance, and flight test results of varying durations. The method described is an extension of one previously developed for single engines. A worked example is given and management control techniques for assuring data integrity are discussed. The Appendix consists of the mathematical derivation of the system reliability estimates.

Design review is becoming a basic requirement during the design and development of military systems. The main purpose of the design review is to increase the system's inherent and operational reliability. The major portion of this paper is the result of reliability's effort to comply with Paragraph 3.6 of NPC 250-1 Reliability Program Provisions for Space Contractors. The design review to be discussed is a reliability circuit design review with emphasis placed on what should be reviewed and the review techniques employed. The basic circuit design review prerequisites, component parts and their ratings, are discussed at the beginning of this paper. The remainder deals with the organization and reviewing of circuits. The review items include worst-case circuit performance, component applications, failure mode analysis, noise rejection, electrical stress, and the determination of component temperatures. Many examples are included to illustrate how each item was accomplished.

We analyse 635 set-years of service experience of 147 merchant-marine steam-turbine-gear propulsion sets, finding an MTBF of 23.5 set-years. The sets of one good-sized fleet have 3 times as large an MTBF as the rest of the sample, a fine return on the more conservative attention paid them. The sample size increased linearly with date. The most satisfactory analysis was as a plot of age-wise cumulatives of failures and service-life. This detected a significant short relatively trouble-free wear-in period with an MTBF of 9.3 set-years; later service had a 27.6 set-year MTBF. We discuss many failure modes and the design and operating practices that minimize them. Much of the favorable MTBF comes from avoiding all but a very little innovation in the design of individual sets.

As an introduction, the paper shows that for spacecraft systems to be designed for the next generation of scientific missions, the system complexity and long life requirements produce reliability criteria which can not be met by either current satellite logic circuitry nor application of redundant sets of such circuitry. The paper then describes a circuit composed of available integrated circuits along with a passive voter circuit and providing majority voting at the logic element level. This circuit is analyzed both from reliability and performance standpoints to show that approximately two to three orders of magnitude improvement in reliability without any significant degradation in performance is realizable.

Three separate and distinct electrolytic and one galvanic process were identified by visual inspection, metallographic, electron microprobe, and x-ray diffraction analysis in a clocked, flip-flop integrated circuit flat pack and/or the associated printed circuit test jig (two on flat pack and two on circuit board). These four processes were all found to be detectable by the use of noise measurements in microvolts per root cycle at 1000 Hz (cycles per second). The direct current applied for noise measurement to the integrated circuit devices was 100 micro-amperes, as compared to the 6-8 milliamperes required for normal operation. After initial experimentation, the devices were caused to fail in a laboratory ambient environment, followed by an acceleration of the rate of electrolytic reaction through the use of essentially 100 percent relative humidity, versus the upper specification limit of 80 to 98% relative humidity.

The techniques of device manufacturing control and screen testing employed today allows an escape rate of latent defects which makes probability of mission success of a manned interplanetary mission questionable. The increased system complexity and mission duration underscore the need to establish maximum integrated circuit reliability and a test sequence to prove that it exists. This paper describes a technique of utilizing life distributions of Integrated circuits obtained under high-stress testing to establish reliability screening criteria. Discussed are the basic factors controlling observable lot behavior, what can be learned from them, and how they dictate a test approach. Analyzed are the typical life expectancy distributions obtainable from today's devices; what the probable escape rates of defective devices are; how they may be made observable; and finally, how the expected life of accepted devices may be altered by stress screening.