Reliability HotWire: eMagazine for the Reliability Professional
In this issue:

Issue 13, March 2002

*Hot Topics
*Reliability Basics
*Tool Tips
*Hot News
*From the Edge
*Share Your Experience

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Hot Topics  
Using Reliability Information Throughout the Organization
The information generated via a reliability engineering program or from other life data analysis activities has a usefulness that extends beyond the group that generated it. It should seem obvious that information regarding the failure behavior of a product would be useful to groups in an organization other than just reliability engineers. However, it is a sad but true fact that some organizations use the reliability information on their products for little more than a specification check. In this article, we will take a look at how life data can be used in other parts of a manufacturing or business organization.

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Reliability Basics  
The purpose of this section is to offer background and advice to the novice reliability engineer.

Defining Distributions - Part 2: Deriving Reliability Functions
In last month's Reliability Basics, we took a look at the mathematical function that is the basis for many useful reliability and life data metrics, the probability density function, or pdf. The pdf function is essentially a continuous form of a histogram, which is a bar chart that characterizes the relative frequency of an occurrence. In this month's article, we will look at how the pdf is used to derive other frequently-used life data metrics. 

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Tool Tips  

The Tool Tips section addresses helpful hints and frequently asked questions about ReliaSoft software products.

  • How can I install Weibull++ Version 5.0 on my new PC that is running Windows 2000?

  • What are the data requirements to perform an analysis in ALTA?

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Hot News
*    MSG-3 Maintenance Program Creator in Beta Testing - ReliaSoft's MPC 3, an MSG-3 compliant maintenance program creator, is currently in the final stages beta testing. Developed with Honeywell Aircraft Engines & Systems Group, this software package is specifically designed for the aerospace industry. Current scheduled release date is early April 2002. For more information, see
*    Next Seminar in Tucson, May 20 - 24 - The next ReliaSoft "Master the Subject, Master the Tools" seminar will be held in Tucson from May 20 - 24, 2002 at the Sheraton Hotel and Suites. For more information on course content and how to register, see
*    ReliaSoft at MRO - ReliaSoft will be participating in the Maintenance, Repair and Overhaul (MRO) Conference and Exhibition, to be held April 9 - 11, 2002 at the Phoenix Civic Plaza and Convention Center in Phoenix, Arizona. ReliaSoft will have a booth in the vendors area where you can get information on ReliaSoft's products and services. For more details, see
*    Accelerated Testing Training - ReliaSoft will again teach the RAC's Accelerated Testing Training Course on March 12 - 14, 2002 in San Diego, CA. Topics for this course include accelerated life testing and how it is applied, overview of stress loading models and analysis, applicable stress-life relationship models and predicting reliabilities, warranty times and MTTFs (MTBFs) using accelerated life data. For more information on course content and how to register, contact RAC at 1.888.RAC.USER or +1.315.337.0900.
*    Reliability Training at GM Knowledge Center - We are pleased to announce that once again ReliaSoft will be providing training classes for GM employees at the General Motors Knowledge Center in Warren, Michigan. The courses offered will cover three diverse disciplines of reliability engineering and include life data analysis, accelerated life test data analysis and system reliability, maintainability and availability analysis. For more information, visit the GMU Knowledge Center Web site at or contact ReliaSoft at +1.520.886.0410. Class size is limited. GM suppliers should check with GM for class availability. The remaining 2002 class schedule is as follows:

May 6 - 8, 2002 - Life Data Analysis
May 9, 2002 - System Reliability
August 5 - 7, 2002 - Life Data Analysis
August 8, 2002 - Accelerated Life Testing
October 14 - 16, 2002 - Life Data Analysis
October 17, 2002 - System Reliability

From The Edge  
In addition to the monthly Reliability HotWire, ReliaSoft publishes Reliability Edge, a printed journal that includes articles and information related to the field of reliability engineering. Articles of interest in the current edition:
  • Analyzing Accelerated Test Data with Time-Varying Test and Use Stress Profiles - Accelerated testing is becoming more widely used in order to obtain life data in a relatively short amount of time. The use of sophisticated tools, such as ReliaSoft’s ALTA PRO software, allows the reliability engineer to design and analyze tests that would have been impossible to do a few years ago. This is particularly true if the test or use stress varies with time. In this article, we will look at an analysis in which the test and the use stress levels have different time-varying profiles. See
  • Competing Failure Modes Analysis - For many products, there are multiple failure modes that can result in the failure of an individual unit. When performing reliability analysis on this type of product, you can take the view that each individual unit could fail due to any one of the possible failure modes and, since an item cannot fail more than one time in a non-repairable system, that there can only be one failure mode for each failed unit. Competing failure modes analysis, which segregates the analysis of failure modes and then combines the results to provide an overall reliability model for the product in question, can be used to analyze data of this type. This article presents an overview of competing failure modes analysis and an example to illustrate the techniques. See
Share Your Experience
Reliability Specification Experiences Wanted
Reliability specifications are a central component of most reliability analyses. Despite their central importance, there is wide variation within industry as to the format and meaning of reliability specifications. In many cases, there are serious deficiencies in the specifications on which manufacturers base important business decisions. In a future issue of our printed newsletter, the Reliability Edge, we will examine the reliability specifications that are commonly used in industry today. We invite you to participate by sharing non-confidential/non-proprietary information about the reliability specifications that you work with in your day-to-day efforts. Do you have experience with particularly effective reliability specifications? Have you struggled to educate decision makers in your organization about the inadequacies of the specifications that they have adopted? Have you received specifications from a client that just do not make sense?
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