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

Issue 64, June 2006

*Hot Topics
*Reliability Basics
*Tool Tips
*Latest Software Updates
*Hot News
*Contribute to HotWire

Reliability HotWire is a service of ReliaSoft Corporation

To subscribe or update your e-mail preferences, go to

Hot Topics

Analyzing Warranty Data of Repairable Systems

Systems can be categorized into two basic types: one-time or nonrepairable systems and reusable or repairable systems. In the latter case, under continuous operation, the system is repaired but not replaced after each failure. For example, if a water pump in a vehicle fails, the water pump is replaced and the vehicle is repaired.


A repair of a complex system typically does not make a system as good as new. Generally a repair is just enough to get the system operational again. That is, the repair addresses only what failed and does not restore the system to its original condition when first put into service. When we repair a system doing only what is necessary to get the system operational again, this is called minimum repair. The repairable systems models and methods in RGA 6 are appropriate for the common practical situation where the systems under consideration are not replaced when they fail, but are repaired under the minimum repair strategy and put back into service.


The system under study may be part of a larger system. For example, a transmission is a complex system that is part of a larger system such as an automobile, truck or helicopter. So, in terms of the RGA 6 methods, both the fleet of transmissions and the fleet of vehicles can be analyzed. In this article, we will address fleet analysis directed toward addressing warranty failures.

To read more, see

Reliability Basics

Economical Life Model for Repairable Systems
One consideration in reducing the cost of maintaining repairable systems is to establish an overhaul policy that will minimize the total life cost of the system. However, an overhaul policy only makes sense if the systems suffer from wearout problems. In other words, the β parameter of the Crow-AMSAA model should be greater than 1. Implementing an overhaul policy if wearout is not present is not economically beneficial, because an overhauled unit would have the same or a higher probability of failing compared to a unit that was not overhauled. If we assume that there is a point at which it is cheaper to overhaul a system than to continue repairs, what is the overhaul time that will minimize the total life cycle cost while considering repair cost and the cost of overhaul?

This article presents a methodology, implemented in RGA 6, for estimating the optimum overhaul time based on the Economical Life Model for Repairable Systems.

To read more, see

Tool Tips
  • What does the asterisk on the Plot Setup Titles page in RENO and Weibull++ 7 mean?

  • Can a single block or component be used more than once in a Lambda Predict project?

To read more, see 

Latest Software Updates
New service releases are now available for ALTA (SR 6.5.4), BlockSim (SR 6.5.3) and RGA (SR 6.5.2). To determine the compile revision of the application on your computer, select About from the Help menu. More Software Downloads...


Application Date Created Version
ALTA 6/8/06 6.5.4
ALTA Update 6/8/06 SR 6.5.4
BlockSim 5/25/06 6.5.3
BlockSim Update 5/25/06 SR 6.5.3
RGA 6/8/06 6.5.2
RGA Update 6/8/06 SR 6.5.2
Hot News
* XFRACAS to be Released Soon   This summer, ReliaSoft will be releasing the latest version of our Web-based FRACAS system. XFRACAS (formerly QTMS) supports the entire incident management process, from the initial development stages to complete tracking of fielded serialized units. It includes complete support for all FRACAS/DRACAS activities and a configurable array of problem resolution processes (from 4 to 8 steps) such as 8D problem resolution, Six Sigma DMAIC, and others. The flexibility, configurability and power of XFRACAS are guaranteed to meet the most demanding needs of FRACAS users. Please contact us for more information or to schedule an online demonstration.
* San Diego MSMT Right Around the Corner The August 28 - September 1, 2006 MSMT seminar in San Diego is coming up soon. Typically, due to the popularity of the course and the popularity of the destination (who can resist San Diego in the summertime?), the course fills to capacity. For those seriously considering this event, please make your reservations early to avoid scheduling issues.
* New On-Site Course Offered - Our rich and expanding array of courses now includes a new on-site course: RS 523: Application of Fault Tree Analysis for Risk Analysis and Repairable System Analysis using BlockSim FTI. The course discusses the application of fault tree analysis for risk analysis and system reliability/availability analysis, with hands-on examples using ReliaSoft's BlockSim FTI software. Topics include fault tree construction and analysis, advanced fault tree gates, common cause failures, minimal cut sets, load sharing, standby, preventive maintenance, availability analysis and more. For more details about RS 523, see If you are interested in scheduling an on-site course for this or any other subject, please contact us.
Public Training Event Calendar
June 2006
June 14 - 16, 2006: International Applied Reliability Symposium in Orlando, Florida
June 26 - 30, 2006: MSMT Foundations in Warsaw, Poland
August 2006
August 7 - 8, 2006: RS 401(C) Life Data Analysis (Condensed) in New Delhi, India
August 28 - September 1, 2006: MSMT Foundations in San Diego, California
September 2006
September 13 - 14, 2006: International Applied Reliability Symposium in Kuala Lumpur, Malaysia
September 18 - 20, 2006: RS 522 Advanced System Analysis in Tucson, Arizona
September 18 - 22, 2006: MSMT Foundations in Manchester, UK
September 21 - 22, 2006: RS 470 FMEA/FMECA in Tucson, Arizona
Contribute to HotWire
Contributions Welcomed
As always, your feedback and contributions are appreciated. ReliaSoft is able to provide the most user-friendly reliability software packages and support because we listen to our customers. This applies to our newsletters and publications as well. We welcome any suggestions or contributions you may have for Reliability HotWire. If you have a topic or article that you think would be useful to the readers of Reliability HotWire, feel free to contact us.

Copyright 2006 ReliaSoft Corporation, ALL RIGHTS RESERVED