Q: How can I find out about your software validation and QA practices?

A: Refer to our Statement Regarding Standard Software Validation & QA Practices, which presents our software validation and quality assurance practices.

Q: How do I get the latest software updates?

A: An integral part of ReliaSoft's continuous improvement process involves issuing updates for all of our products to address technology changes, functionality requests and/or issue resolutions. Same version software updates (i.e. same major version number such as 6.X.X) are made available to all licensed users free of charge. We encourage you to update your product when a new update is released.

Service releases are available via the ReliaSoft.com Web site. Consult the product home page for the product of interest or consult the Reliability Software Downloads table for updated information.

Q: Where can I get information on the theory behind the calculations and analyses being performed in ReliaSoft applications?

A: In addition to the software User's Guide, ReliaSoft's standard software packages come with an additional reference text that explains the theory and background of the calculations being performed by the particular application. Many users have found these reference texts to be an invaluable tool for increasing their understanding of the concepts behind the reliability analyses they regularly perform. These texts can also be purchased separately from the software. For ordering information, see http://www.ReliaSoft.com/RSPub.htm.

Additionally, ReliaSoft provides free on-line versions of some of these reference texts that can be accessed from ReliaSoft's reliability engineering resources Web site at http://www.weibull.com. These include:

• Life Data Analysis Reference (for use with Weibull++) - http://www.weibull.com/lifedatawebcontents.htm
• Accelerated Testing Reference (for use with ALTA) - http://www.weibull.com/acceltestwebcontents.htm
• System Analysis Reference (for use with BlockSim) - http://www.weibull.com/systemrelwebcontents.htm
• Reliability Growth Reference (for use with RGA) - http://www.weibull.com/relgrowthwebcontents.htm

A: Yes. ReliaSoft provides special "bundled" pricing options for users who purchase both software and training. Complete details are available at http://www.ReliaSoft.com/bundles.htm.

Q: Can I speed up the data entry process in Weibull++ and ALTA?

A: There are some shortcuts available in Weibull++ and ALTA for speeding up the data entry process.

In a Data Sheet that is configured for grouped data entry, it is not necessary to enter a value for the "Number in Group" if the value is 1. Weibull++ and ALTA will automatically insert the value of 1 for the cells that are left blank in the "Number in Group" column.

Another shortcut can be used when a "State F or S" column is displayed in the Data Sheet. In this case, the cells in the "Time Failed" column can be entered first. When a positive value is entered, Weibull++ and ALTA automatically insert an "F" in the corresponding "State F or S" column position. When a negative value is entered, the applications automatically insert an "S" in the "State F or S" column. For example, for a right censored item at 100 hrs, type "–100" in the "Time Failed" column. An "S" will automatically be inserted into the "State F or S" column.

These applications also provide a variety of copy/paste and import capabilities to obtain data from existing data sources.

Q: Can I display the locations of suspensions on my probability plots?

A: Yes, relative locations of suspensions can be displayed along the x-axis of plots in Weibull++ 7 or ALTA 7 (Standard and PRO). You can set this option by selecting Plot Setup from the Plot menu or clicking the Plot Setup icon in the Plot Sheet Control Panel and clicking the Lines tab in the Plot Setup window. In the second drop-down menu in the Name field, select Suspended Points and then select the Show Points option in the area to the right. With this option selected, the suspensions will appear on the x-axis of of the plot. You can use the other options on the Lines page to configure how the suspensions are displayed.

Q: How do I remove the Program ID from the plots in Weibull++ and ALTA?

A: The Program ID, or upper title, appears in the upper left corner of plots in Weibull++ and ALTA, and contains information about the software and ReliaSoft. This text, along with the other titles on the plot, can be altered or removed via the Plot Setup. Select Plot Setup from the Plot menu or click the Plot Setup icon in the Plot Sheet Control Panel and clicking the Titles tab in the Plot Setup window. Select or deselect the Show box next to each input box to determine whether the title will be shown on the plot. Each asterisk (*) represents the title defined in the Set Default Plot Titles window. If you type new text in an input box, either instead of or in addition to the asterisk, the text you type will be displayed on the plot instead of or in addition to the default text. To use your changes as the default for all subsequent plots, click the Set as Default button on the right side of the window. To change the default text for the current plot type or another plot type, click the Default button at the bottom of the Titles page to open the Set Default Plot Titles window.

Q: How can I show information from more than one data set on one plot in Weibull++ and ALTA?

A: Weibull++ or ALTA Folios that contain more than one data set can easily display data from multiple sources using the MultiPlot feature. Once the data sets of interest have been entered and analyzed, you can add a MultiPlot to a Standard Folio or to the project. To add a MultiPlot to a project, select Add Additional Plot then Add MultiPlot from the Project menu. You will be prompted to select the Folios/Data Sheets that will appear in the plot. To add a MultiPlot to a Standard Folio, select Insert MultiPlot Sheet from the Folio menu. In this case, the Data Sheets in the Standard Folio will be automatically selected for inclusion in the MultiPlot. You can change this selection using the Select Data Sheets button in the MultiPlot Control Panel.

Once you have selected the Data Sheets that will appear in the plot, specify the rest of the plot properties. In order to be available for inclusion in a MultiPlot, the Data Sheet must have been calculated and, for probability plots and contour plots, the Data Sheets must have been calculated with the same distribution. For example, if you have a data set that has been analyzed using the lognormal distribution, it cannot be displayed on a Weibull probability plot. This is because probability plots are constructed specifically for one type of distribution.

Note that in Weibull++, Warranty Folio Data Sheets can also be included on MultiPlots.

Q: How do I avoid having borders on my printed plots in Weibull++ and ALTA?

A: You can set this option by selecting Plot Setup from the Plot menu or clicking the Plot Setup icon in the Plot Sheet Control Panel and clicking the Appearance tab in the Plot Setup window. Select or clear the checkbox beside the Border option in the Plot area to show or hide the outline on the plot.

In addition, when printing the plot from the RS Draw utility, you can de-select the Print Border option in the RS-Draw Graphic Print window. Note that the setting in the Plot Setup has no effect on graphs printed from RS Draw, and vice versa.

Q: Is there a way that I can display probability scales on the probability plots in Weibull++ and ALTA?

A: Probability scales allow the user to read parameter estimate values directly from the probability plot. To toggle this feature on or off in Weibull++ or ALTA, select Show/Hide Items from the Plot menu or the Plot Sheet shortcut menu (accessible by right-clicking inside the plot area). In the Show/Hide Plot Items window that appears, select the Scales checkbox beside the Probablility Scales option in the Other area and then click OK. This will show the probability scales appropriate to the selected distribution on the probability plot.

Q: How can I determine the confidence bounds on parameter estimates in Weibull++ and ALTA 

A: Confidence bounds on parameter estimates in Weibull++ and ALTA can be obtained through the Quick Calculation Pad (QCP). Once a data set has been entered and analyzed, open the QCP, go to the Confidence Bounds tab and select Show Confidence Bounds then select the type of confidence bounds you wish to display for the parameter estimates. Once you have selected the type of confidence bounds, go to the Parameter Bounds tab and click the Calculate Bounds button. This will display the parameter estimates as well as the selected confidence bounds.

Q: What is the DRT (Design of Reliability Tests/Testing) utility in Weibull++  and ALTA and how can it be used?

A: The DRT utility allows you to determine the required numbers of units and/or test time required to demonstrate a certain reliability result. It is a useful tool when you need to evaluate the number of units, the test time required under a certain testing scenario or the reliability and confidence that can be demonstrated if such a scenario is actually implemented. The utility uses the binomial distribution (and in Weibull++ version 6 or later, the reliability equation) to perform the required calculations. There is also functionality for test design for units with an assumed exponential distribution.

Q: When using the Tests of Comparison utility (Comparison Wizard) in Weibull++  and ALTA, is it appropriate to change the lower limit to something other than zero on the Setup tab?

A: No, the lower limit should be equal to zero. The tests of comparison utility has been designed to compare data sets over their entire life spans, starting at time t=0.

A: Weibull++ 5.0 uses median ranks to calculate the points for the plot. Weibull++ 6 and 7 use median ranks or Kaplan-Meier estimates. For a more detailed discussion of the use of median ranks for plotting, see ReliaSoft's Life Data Analysis Reference on the following topics. The reference is also available in an on-line version on weibull.com.

ALTA 7, ALTA 6 Standard  and ALTA 1.0 provide five life-stress relationship models: Arrhenius, Eyring, Inverse Power Law, Temperature-Humidity and Temperature-NonThermal. The Arrhenius, Eyring and Inverse Power Law models are single stress models. Temperature-Humidity and Temperature-NonThermal are combination models, which allow you to analyze the effect of two stresses simultaneously.

ReliaSoft's ALTA 7 PRO and ALTA 6 PRO provide three additional, more complex, models that support the analysis of data with up to eight simultaneous stress types or with stress profiles that vary with time: Proportional Hazards, General Log-Linear and Cumulative Damage. Transformations available for the general log-linear model or the cumulative damage model include the power, exponential and, new in version 7, Arrhenius relations. 

The life distributions and life-stress relationships available in the ALTA software are discussed in more detail in ReliaSoft's Accelerated Testing Reference, which is also available in an on-line version on weibull.com.

A: With the cumulative damage life-stress relationship selected in ALTA 7 PRO, right-click a cell in the stress column to display a list of the stress profiles that have been defined in the project. You can select a profile from the list and click Add. Stress profiles are added to the project in much the same way as Folios.

Note that this feature is available only with the cumulative damage model in ALTA PRO.

In ALTA 6 PRO, stress profiles are managed in libraries, which can be attached to projects.

Q: Does BlockSim handle k-out-of-n parallel redundancy configurations?

A: Yes. This functionality is controlled by the use and configuration of the nodes in BlockSim. Lines going out from units in parallel can end in a node. A node is a block that usually has no failure characteristics (although they can be assigned failure characteristics in BlockSim). Double-click the node block to open the Node Properties window, where you can assign how many paths out of the parallel units must be functioning in order for that part of the system to operate. In this way, k paths out of n units can be assigned.

Q: How can I repeat the results I get when performing simulations in BlockSim?

A: The reliability and maintainability simulations in BlockSim rely on a random number generator to perform the analyses. Consequently, if you perform consecutive analyses on the same system without specifying a seed for the random number generator, the results will differ each time you run the simulation. If repeatable results are desired, be sure to select the Use Seed option on the Maintainability or Reliability tab of the Reliability/Maintainability Simulation window and specify the value to be used as the seed.

Q: In BlockSim, how can I simultaneously change the values of more than one block in the RBD?

A: In order to change the values in more than one block, highlight the collection of blocks of interest. This can be accomplished either by dragging a box around the group of blocks you want to change, or by clicking the individual blocks while simultaneously holding down the Ctrl key. Double-click the highlighted blocks to begin editing (a message box will pop up to inform you that you are changing the values of more than one block). Note that once the changes have been entered, the blocks will have the same values for all parameters, even parameters that were not changed during the editing process.

Q: How do I obtain component failure and repair information for RBD blocks in BlockSim?

A: The recommended way to obtain failure and repair information is through empirical testing. This may be through in-house testing of components and parts or from information supplied by the vendor. ReliaSoft takes the position that this type of directly-obtained component information is the best way to represent the failure and repair characteristics of the components, and consequently will produce the best results for the system-level analysis.

However, ReliaSoft recognizes that this information may not always be available for those who wish to perform a system reliability analysis. This may be due to a lack of affordable parts for testing early in the development process or simply due to the desire to "blue sky" and play around with potential design configurations without having to undergo costly testing procedures. Consequently, BlockSim can also import generic failure rates from the PRISM database. The PRISM software has the next generation of electronic component failure rate models and a comprehensive searchable database of observed field failure rates modeled after the successful NPRD and EPRD data book series. The PRISM concept accounts for the myriad of factors that can influence system reliability, combining all those factors into an integrated system reliability assessment resource. For more information about BlockSim's integration with PRISM, see http://BlockSim.Reliasoft.com/prism.htm.

Q: How can I quickly insert identical units in series in a BlockSim reliability block diagram?

A: Identical blocks in series can be inserted automatically using BlockSim's Add Block to Diagram command. Simply select an existing block in the diagram and select Add Block to Diagram from the Diagram menu or click the icon.

A new block, with the same style and properties as the selected block, will be created in the diagram. The new block will be placed to the right of the original block and connected with a relationship line.

Q: How can I copy a portion of a reliability block diagram (RBD) into the same diagram sheet in BlockSim?

A: Entire RBDs or sections of RBDs can be copied and pasted into the same diagram sheet in BlockSim simply by clicking the diagram sheet outside the blocks and dragging an outline around the section of interest. This will highlight a group of blocks that can be copied by selecting Copy from the Edit menu or by pressing Ctrl+C. By selecting Paste from the Edit menu or pressing Ctrl+V, the entire section of blocks (with connections) will be pasted back into the same diagram sheet and additional blocks and connections can be inserted to link this portion of the diagram with the original section of blocks. 

Q: Is there an easy way to align the blocks in BlockSim?

A: BlockSim's Align Objects tool allows you to align selected blocks in relation to the top, middle, bottom, left, center or right sides of the blocks.

In addition, the Diagram Setup window provides the Snap to Grid option, which automatically aligns the blocks in the diagram sheet to a grid. To access the Diagram Setup, press Ctrl+D or select Diagram Setup from the Diagram menu or Diagram Sheet shortcut menu. The Diagram Setup also allows you to hide or display grid lines in the diagram sheet and change other aspects of the appearance of the diagram.

Q: Can I have circular references in my BlockSim reliability block diagram (RBD)?

A: Circular references are not allowed in BlockSim. The software uses a methodology called the Path Tracing Method in order to evaluate the reliability of the system in the RBD. The Path Tracing Method requires that each RBD has one starting block and one ending block. It then calculates all of the "paths" from the starting block to the ending block that would allow the system to function. For this reason, circular references are not allowed, as it would result in an infinite number of paths through the system. Note: Issue 2 of the Reliability HotWire eMagazine presents a more detailed discussion of methods to determine the reliability of complex systems.

In some circumstances, it may be possible to work around the problem of circular references by splitting blocks, or creating an input block and an output block, which represent two different functions of the same component.

Q: Why do I receive an error message when I export my Xfmea project to an XML file and then try to open the XML file in BlockSim?

A: This question is answered under Xfmea and FMEA/FMECA Analysis.

Q: In RGA 6, can a fixed effectiveness factor be used throughout the analysis instead of specifying individual effectiveness factors for each BD mode?

A: Yes. In the Effectiveness Factor window, click the Use Fixed Effectiveness Factor button on the toolbar. If effectiveness factors are defined in the Spreadsheet area of the window, then when you click this button, the input box will display the average effectiveness factor, which is also displayed in the status bar at the bottom of the window. You can use this value or enter a new value into the input box. This value must be less than 1.

Q: What are the requirements for defining system configurations in MPC 3?

A: MPC 3's System Hierarchy has been designed to fit the Air Transport Association (ATA) definitions for aircraft groups, systems and subsystems (described in the document ATA iSpec 2200: Aircraft Systems). Therefore, the following constraints apply:

• There is a maximum of four levels in the system hierarchy: system, subsystem, sub-subsystem and part.
• The system numbers are intended to be based on the ATA iSpec2200 where, for example, 21 represents Air Conditioning, 23 represents Communications, 34 represents Navigation and so on.
• The subsystem numbers are intended to be identified in multiples of ten (i.e. 10, 20, 30, 40, etc.) based on the ATA iSpec2200 where, for example, 21-10 represents the Compression subsystem of the Air Conditioning system and 34-30 represents the Landing and Taxiing Aids subsystem of the Navigation system and so on.
• The subsubsystem numbers are intended to be defined within the range specified by the subsystem. For example, for any subsystem #10, the numbers 11 through 19 are valid to define the sub-subsystems.
• The "ATA Number" that is presented in the print-ready reports will consist of four (or more) numbers, in which the first two numbers are determined by the system, the third number is determined by the subsystem, the fourth number is determined by the sub-subsystem. Two or more additional numbers may be used to represent parts. For example, the ATA# 231500 represents the following system configuration:
  • System = 23 Communications
  • Subsystem = 10 Speech Communications
  • Sub-Subsystem = 15 SATCOM
• In CRV 3.0.11, ReliaSoft added the ability to use the "extended" MSI number format in print-ready report output. If this option is selected on the Report Properties page of the User Setup, the first two numbers are determined by the system, the third and fourth numbers are determined by the subsystem and the fifth and sixth numbers are determined by the sub-subsystem. For the example given above, this would be 231015.

Q: Why are the MSI selection questions disabled in MPC 3?

A: The MSI selection questions are available only at the lowest level of the system hierarchy; answers made at that level are then "rolled up" to the higher levels. If, for example, you have a hierarchy with a system, a subsystem and a sub-subsystem, MSI selection questions will be available only for the sub-subsystem. If you have assigned one or more parts below that sub-subsystem, however, the selection questions will be available only for those parts and the answers to the questions will apply at all levels above the parts. This is based on the assumption that if any component of an assembly poses, for instance, a safety risk, then the entire assembly also poses a safety risk, and so on. A Yes answer for any question for any part will identify the subsubsystem as a Maintenance Significant Item in the software and in the report output.

Q: In Xfmea Standard, why are the Add and Delete buttons disabled in the Profiles/Libraries Management window? I am also unable to edit any of the profiles.

A: This will occur if the active library is Read-Only for the user. To test this, go to the Other page of the User Setup and determine the location/filename for the active library file (*.lib). Then determine whether the user has Read/Write access to this file. If not, give the user Read/Write access (e.g. place the file in a directory that the user has Read/Write access to and/or open the Properties window for the file and de-select the Read-only option) or choose a different library to be active.

Q: Why do I receive an error message when I export my Xfmea project to an XML file and then try to open the XML file in BlockSim?

A: You will receive an error message in BlockSim when you try to open an XML file that was created in Xfmea if at least two higher level items in the Xfmea project have the same name. This is because any item that has one or more sub-items is represented as a subdiagram in BlockSim and the diagram names in BlockSim must be unique. This will also occur if the project and a higher level item have the same name because the project is also represented as a diagram in BlockSim.

When you receive this error message in BlockSim, you will be asked if you want to see the error report. Click Yes so you can identify the errors in the XML file. You may be prompted to enter a path for the word processor that will display the error report. Type the pathname for an application on your computer that can open a text file (e.g. Notepad, WordPad, etc.). For example, enter C:\Windows\System32\Notepad.exe. (Please note that if this is not a valid pathname/filename on your computer, then the report will not open.) Click OK. The report will automatically open in the specified application with a list of the errors that have been found in the XML file. You can then go back to your Xfmea project and correct these errors, export the revised project to XML and then open the XML file in BlockSim.

Q: How do I replace the logins for existing Xfmea Enterprise user accounts if my company's domain name changes?

A: Since Xfmea Enterprise uses Windows NT Authentication, if the company's "domain" changes, the administrator will need to replace the SQL Server Logins for existing Xfmea Enterprise users to reflect the new domain name. See Technical Support document # RS40001 for detailed instructions.

Q: How can I print column headings on every page of a report generated by Xfmea or RCM++?

A: There is an option to set this automatically for reports generated in Microsoft Excel and a workaround to apply this to reports generated in Microsoft Word. See Technical Support document # RS40003 for detailed instructions.

Q: What are the minimum database maintenance recommendations for my Xfmea Enterprise database?

A: With enterprise-wide systems such as Xfmea Enterprise, it is important to have established procedures to assure that proper database maintenance and backup activities are being performed. Technical Support document # RS40005 present's ReliaSoft's recommendations for the minimum database backup and maintenance activities that should be performed in SQL Server to protect the organization's data and keep the system running smoothly.

Q: What should I do to protect my data in an Xfmea Standard or RCM++ database?

A: ReliaSoft's Xfmea Standard and RCM++ software products work with Microsoft Access® databases in the back end for storing analysis data. These database and library files (*.rx4 and *.lb4) will be subject to the same limitations and vulnerabilities as any other Access® database. Therefore, Technical Support document # RS40010 provides some recommendations for standard precautions that all users can take to protect the data in their Xfmea Standard or RCM++ databases from this type of corruption and reduce the impact of the data loss if corruption is unavoidable.

Q: Why doesn't Xfmea/RCM++ provide a Save command?

A: ReliaSoft's Xfmea Standard , Xfmea Enterprise and RCM++ software products are database-driven applications that store data in a relational database on the back end and have the potential for simultaneous access by multiple users. Therefore, the software behaves somewhat differently than a Microsoft Word® document or Weibull++ project file that can be edited by only one user at a time. One of the differences is in how the analysis data is saved. In Xfmea and RCM++, your changes are saved whenever you click OK to close a properties window and, when working in the FMEA Worksheet View, whenever you navigate away from the cell you were typing into. The software does not provide a separate Save command in the File menu (like Word or Weibull++) because in Xfmea/RCM++, your changes are saved automatically while you're updating the analysis.

Q: How do I turn off the RPNs in the DRBFM Utility?

A: The Design Review Based on Failure Mode (DRBFM) utility in Xfmea and RCM++ includes Risk Priority Number (RPN) columns if those columns have been activated for the associated FMEA. The workaround for users who wish to use the RPN columns for FMEAs but not for DRBFMs is to disable the RPN options in the Project's Interface Style when you are working with DRBFMs and then enable the RPN options again when you are working with the FMEA. See Technical Support document # RS40009 for detailed instructions.

Q: How does ReliaSoft's Criticality Analysis calculation method differ from the original MIL-STD-1629A and why?

Q: Why don't Xfmea and RCM++ record a separate Detection rating for each Control?

A: There is no benefit to calculating a separate RPN for each Control, since there is no need to prioritize Controls for corrective action. If there are multiple Controls in place for a single Cause then even if each Control is rated separately, there must be some way to select a single Detection rating that will be used to calculate the RPN for the Cause, which is the actionable level of the analysis. Some analysts may choose to rate each Control and select the lowest rating but many will choose to take all Controls into account and assign a single overall rating. See Technical Support document # RS40007 for a detailed explanation of the approach taken in Xfmea and RCM++.

Q: Why does RCM++ place Effects before Causes?

A: The RCM++ software supports all 7 questions required for an RCM analysis but it considers the questions in a different sequence than the SAE JA1011 and JA1012 guidelines recommend. The reasons for this include 1) consistency with FMEA/FMECA and MSG-3 analyses, 2) intuitiveness and convenience of placing the Cause (Failure Mode) adjacent to applicable actions/tasks and 3) efficiency of defining and categorizing an Effect one time when it is the same for multiple Causes (Failure Modes). See Technical Support document # RS40002 for a more detailed discussion of this issue.

Other FAQs for RCM++ are presented under Xfmea and FMEA/FMECA Analysis listed above.

Q: What are the minimum database maintenance recommendations for my database?

A: With enterprise-wide systems such as XFRACAS, it is important to have established procedures to assure that proper database maintenance and backup activities are being performed. Technical Support document # RS40005 present's ReliaSoft's recommendations for the minimum database backup and maintenance activities that should be performed in SQL Server to protect the organization's data and keep the system running smoothly.