Reliass Reliabilty Safety Software: Managing Reliability Across All Product Lifecycle    
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RAM Commander








********See also ASENT R & M ToolKit for a Powerful Client/Server alternative********



RAM Commander  is a comprehensive software tool for Reliability and Maintainability Analysis and Prediction, Spares Optimization, FMEA/FMECA, Testability, Fault Tree Analysis, Event Tree Analysis and Safety Assessment. Its reliability and safety modules cover all widely known reliability standards and failure analysis approaches. RAM Commander is indispensable tool for ensuring reliability of sophisticated systems.

Modules cover:

Reliability Prediction

Reliability Block Diagram with Monte Carlo Simulation

Maintainability - RCM

Spare Parts Analysis & Optimisation
Markov Chain

Derating Guidelines and Reports

Stress - Strength Analysis


FMECA Analysis

Testability Analysis

Process & design FMEA
Fault Tree Analysis (FTA)

Event Tree Analysis (ETA)
Safety Assessment - based on SAE ARP 4761

Master Minimum Equipment List (MMEL)

RAM Commander is modular software allowing a customer the flexibility of gradual addition of the modules to the package in accordance with the requirements of a project or the budget constraints.

Prediction Methods
TR332 - Bellcore Issue 6
SR332 - Telcordia 2001
RDF 95 - French Telecom
UTEC 80810 (CNET 2000)
HRD - British Telecom
GJB299 - Chinese Standard
IRPH93 - Italtel
RADC 85-91
NSWC-98/LE1 Mechanics
Siemens SN 29500-1
IEC 62380
Reliability Prediction              

RAM Commander provides everything necessary for primary reliability prediction based on one of the prediction models for electronic equipment, mechanical and electro-mechanical equipment. Graphical presentation of the projects Product Tree allows visibility and easy data manipulation.

Product Tree Table.

Performing reliability allocation, Pareto analysis, RAM sensitivity analysis producing temperature curves and mission profile are extremely easy with RAM Commander.

RAM Commander produces all commonly required reliability reports and allows the user to define customized reports.
RAM Tasks
Sensitivity analysis & trade-offs
R & M allocation/apportionment
RAM Data management
Field failure rates conversion
Mission Profile Analysis
ILS/LSA Support
RBD with Monte Carlo simulation
Reliability estimation of various system configurations
Spare Parts optimization
Derating guidelines and reports
Fault Tree Analysis
Risk Analysis

Pareto Report. Pareto analysis identifies components or component families that contribute most significantly to system or assembly failure rate - about 80% of total failure rate

Temperature Curve Report. Presents the failure rate or MTBF as a unction of temperature: regular, multi-environment & multi-items on one graph.

Field Failure Rate Module

Reliability Block Diagram (RBD)                                                     

RBD module allows performing the functional Reliability and Availability analysis of systems with variety of reliability distributions, and types of redundancy and repair factors. While the basic RAM Commander module provides the reliability calculations and predictions for non-redundant systems, RBD utilizes data defined in the basic module, and performs either analytical calculation or Monte Carlo simulation depending on the type of a reliability configuration of the system.

RBD-supported configurations
K-out-of-N with active (hot) redundancy
K-out-of-N with stand-by (cold) redundancy
Partially loaded K-out-of-N - warm redundancy
K-out-of-N w/repair, w/o repair, w/restricted repair
K-out-of-N with Switch

The analytical technique is used mostly for exponential distributions. For each RBD, a graph of the reliability function R(t) can be drawn and MTBCF (Mean Time Between Critical Failures) can be calculated using numeric integration.

Monte Carlo simulation with its' high speed, accuracy, and large number of steps allows to evaluate Reliability and Availability for arbitrary configurations when there is no analytical solution, i.e. complex configurations, including standby, partially loaded and active redundancy; full or restricted repair with non-exponential distribution of time-to-repair; analysis under non-steady, transient state; dependent RBD elements; analysis of periodical inspection policy.

Reliability Block Diagram and MTBCF graph

System Configuration
feature of the RBD module is an ingenious answer to the requests of our customers who need to compare the reliability and availability of various system configurations created as the sub-sets of the project product tree. The creation of the unlimited number of system configurations, easy transformation of each configuration into an RBD, MTBCF calculation, synchronized with the product tree changes, and finally a clear and elegant graphical presentation - all this makes the System Configuration feature an invaluable addition to the RAM Commander performance.

System Configuration Table.


Maintainability Prediction and Analysis in RAM Commander is based on the MIL-HDBK-472, Procedure V, Method A. Maintainability module is used to predict maintainability of systems and equipment of any type, including avionics, ground and shipboard electronics, mechanical equipment, etc., at all levels of maintenance.

Maintainability procedure definition

Maintainability Module Features
5 customizable levels of Repair and Replace for tree elements
Corrective Maintenance procedure per element or Failure Mode
Preventive Maintenance procedures per element or Failure Mode
Preventive Maintenance procedure frequency optimization
Standard Times and Standard Tasks libraries
List of required skills, equipment and materials for each task
Skills, Equipment and Materials Libraries
RCM (Reliability-Centered Maintenance)
A wide range of reports for Maintainability Analysis
Required skills, materials and equipment calculation


Maintenance Engineering Analysis report

Spare Parts analysis and optimization:                                                                 

RAM Commander Spare Parts Analysis and Optimization is based on two cost optimization criteria: Total No Shortage Probability & Availability. The module performs Cost-Availability optimization of repairable and discardable parts for all levels of repair. Spare Parts Analysis and Optimization module takes into account the variety of mission applications, e.g., when the primary restriction is weight or volume, such as for fly-away kits or when no repair or supply of spare parts is permitted (unsupported mission). Data entry for the module is minimized due to the usage of the data used in the RAM project.

Spare Parts Optimization
Markov Chain:                                                                                

The Markov chain technique and its mathematical model have been demonstrated over years to be a powerful tool to analyze the evolution, performance and reliability of physical systems.


RAM Commander's Markov is a powerful tool with the following features:

Up-to-date, intuitive and powerful Markov Chain diagram interface with possibilities of full control over the diagram: elements location, colors, styles, zooms etc.
Convenient ways of diagram printing and simple Copy & Paste transfer to other applications
Calculation of Steady-State Mode
Calculation of Time-Dependency Mode
Calculation of Availability, Unavailability, Failure and Repair rate and frequency, MTBF, MTTF, MTTR, Reliability/Unreliability and other system parameters
Results output:
  o System parameters for selected times as table or graph
  o State probabilities for selected times as table or graph
  o Steady-State results report
  o Transition Matrix report
  o States and Transitions data report
Results export to Excel, Word, HTML formats.

Stress - Strength Analysis                                                                

Stress/Strength Analysis - Structural/Mechanical Analysis of Components and Systems
Stress/Strength analysis method determines the probability of failure based on the probability of stress exceeding strength.
Calculation of Failure Probability (Unreliability) by:
 Distributions of Stress and Strength
 Variation information between Stress and Strength (Factor of Safety n and Variations)

Having distributions of Stress and Strength, we may calculate failure probability (Unreliability):

Having variation information between stress and strength (Factor of Safety n and Variations), we may also calculate the unreliability:


RAM Commander MSG-3 module is used by aircraft manufacturers or aircraft operators (airlines) to perform aircraft Scheduled Maintenance Development analysis according to Air Transport Association (ATA) Maintenance Steering Group 3 (MSG-3) document.

According to ATA, the ATA MSG-3 publication outlines a decision-logic process for determining initial scheduled maintenance requirements for new aircraft and/or power plants. This document presents a means for developing maintenance tasks and intervals acceptable to regulatory authorities, operators and manufacturers. The analysis has the objective to maintain an inherent safety level and to achieve an optimal balance between maintenance costs and reliability.

RAM Commander's MSG-3 module main features:
  Intuitive step-by-step procedure
  Integration with Reliability and FMECA analysis modules
  Interactive decision diagrams
  Final report generation is MS Word
  Customizable MS Word report template

The MSG-3 module is integrated with RAM Commander Reliability and FMECA modules. It divides the procedure into 7 steps including system definition, maintenance significant items selection, failure effect categorization, task selection and development and report generation.

It brings user through the decision-making process using interactive decision diagrams taken from the standard:

As an output of the procedure user gets final report generated in MS-Word with all the data inside. Report is generated based on customizable MS Word template; user may change the template design.


The Derating module is used to analyze the overstress of components under current temperature conditions. The module provides a tool to define Derating curves and identify overstressed components, i.e., those working under stress exceeding the specified rating value. Rating, or maximum rated stress, is the specified value of temperature, power, voltage or current that define the absolute maximum stress limits. Exceeding these values creates a high probability of part damage/failure.

The maximum rating is specified in the part specifications or in standard for this type of part. It is a well known practice in many companies to define limit values of stress for various components as a function of temperature. These limits, "Derating curves", are part of the company policy of component usage. A report created by the Derating
Derating Module Features
Intended for electronic designers Common
database with R &M prediction
User-definable Derating Guidelines
Clear indication of overstressed parts in reports

module includes all components in the selected part of the system, or only the overstressed ones. Derating reports with indication of overstressed parts.

Libraries and Data Import
RAM Commander enables the user to access and use various sources of reliability information: extensive RAM Commander or user-defined component libraries, field data or data imported with the help of Import Wizard.


Failure Mode, Effects and Criticality Analysis (FMECA) is a natural continuation, and in many cases inseparable part of the Reliability Analysis. Previously a separate software package, FMECA is now a fully-integrated RAM Commander module. FMECA module uses a product tree previously created by the user for the reliability analysis purposes.

The RAM Commander FMECA module is suitable for both hardware and functional approaches to FMECA, and fully complies with MIL-STD-1629 A, commercial standards, and Good Manufacturing Practice (GMP) requirements.
RAM Commander FMECA module makes the FMEA process easy and visible: the product tree and the corresponding to each item sequence of Failure Modes => Next Higher Effects => End Effects are totally visible in the same window.
FMECA Libraries
Components - based on FMD-97
Failure Modes
End Effects & Severities
Failure Mode Full Description
Test methods
Extensive use of the FMECA Libraries facilitates the process even more and contributes to the accuracy of the performed analyses and reports. You can perform both the FMEA and FMECA calculating failure mode ratios, conditional probabilities and item criticality numbers.

Testability Analysis      

Testability Analysis sub-module of the FMECA module is intended for in-depth Testability analysis. The main characteristics of Testability - BIT/Detection Coverage and Fault Isolation Resolution - can be calculated for each maintenance level (Organizational, Intermediate, Depot) and for specific detection methods (BIT, BITE, external test equipment, etc.). Test method efficiency and indication are defined for each test method or a group of test methods.
FMECA Standard Reports
Criticality Analysis - MIL-STD-1629
End Effects Criticality
Criticality Matrix
Fault Tree
NHE Critcality
Test methods
BIT/Detection Coverage
Fault Isolation Resolution
Testability analysis is widely used for the development of necessary supporting documentation: maintenance manuals, troubleshooting procedures and inspection requirements.

Test coverage report shows the percentage of failures covered by a chosen test.

Process & Design FMEA                                                                                  

Formerly a separate package, Process and Design FMEA is now fully integrated in RAM Commander. This module performs Process/Design potential Failure Mode and Effects Analysis. The uniqueness of the RAM Commander approach to process/design FMEA is reflected in the graphical presentation of the process flow:

Main window of the RAM Commander Process & Design FMEA

Decompose the system or process into components or sub-processes. For each functional block, define name & function, enter failure mode causes and effects manually or from the libraries. Process & Design FMEA module provides full graphical and textual visibility of the Potential Failure Mode => Cause => Effects chain.

What is A Potential Failure Mode?
The manner in which a component, subsystem, or system could potentially fail to meet the design intent. The potential failure mode could also be the cause of a potential failure mode in a higher level subsystem or system, or be the effect of a potential failure

Edit cause dialog contains corrective actions and RPN (risk priority number

Process and Design FMEA produce all the reports required by PFMEA: design FMEA, Process FMEA, Pareto analysis, regular FMEA with all NHE, basic fault tree

Process/Design FMEA Features
Compliant with AIAG and QS-9000 PFMEA
Supports the concurrent updating of FMEA documents
Compliant with safety and hazard analysis standards
Assures isolation and elimination of all critical failure modes & causes
Facilitates processing of experts' occurrence and detection assessments

Fault Tree Analysis (FTA)                                                                                  

****See also LOGAN Fault & Event Tree Analysis  for an alternative
FT & ET Analysis Tool*****

RAM Commander's FTA (Fault Tree Analysis) software module is the one of the unique features of the RAM Commander. It is simplified FTAnalyzer, fully integrated with RAM Commander product tree, reliability prediction and FMECA. It implements and summarizes the first-hand experience gained by the FTA experts in hundreds of projects using RAM Commander and other software tools from our portfolio.

Main window of the RAM Commander Fault Tree Analysis Module

FTA Features

Up-to-date, intuitive and powerful fault tree diagram interface allowing full control over the diagram: elements location, colors, styles, zooms, etc.

Handy methods for diagram printing and simple Copy & Paste transfer to other applications

Easy to use Events Library

Generation of Minimal Cut Sets

Calculation of Unavailability Q(t), Mean Unavailability Q

Calculation of Importance and Sensitivity

Calculation of Frequency W(t) and Intensity L(t)

Calculation of Unreliability F(t) and Number of Failures E(0,t)
Set of required reports - FTA diagram, MCS, events library etc.
Link between FTA and the product tree

Link between FTA and FMECA modules

Integration with Safety analysis module

Automatically build FTA from FMECA

Automatically build FTA from FMEA

Data import from RiskSpectrum, Aralia SimTree and CAFTA

Fault Tree Analysis is one of the most widely used methods in system reliability and failure probability analysis. A fault tree is a graphical representation of a logical structure representing undesired events ("failures") and their causes. You create the logical structure by using gates and represent undesired events by using basic events. Reliability parameters are assigned to the basic events. Widely used in system reliability studies, fault tree analysis offers the ability to focus on an event of importance, such as a highly critical safety issue, and work to minimize its occurrence or consequence. The probability of the top-level event can then be determined by using mathematical techniques. The resulting fault tree diagram is a graphical representation of the chain of events in your system or process, built using events and logical gate configurations.

FTA Basic Event data

Two types of analysis can be conducted using Fault Trees:
  • Qualitative Analysis: performed by means of Minimal Cut Sets (MCS) building
  • Quantitative Analysis: calculating the Absolute probabilities, i.e. the probabilities of system failures

Example of FTA Unavailability and MCS Analysis report

After Unavailability calculation and MCS analysis, Importance and Sensitivity Analysis may be performed. Importance analysis results help to select those fault tree events, which contribute most to the system's unavailability. Sensitivity analysis helps to choose those events, where a relatively small change will lead to a relatively large system unavailability changes. Calculated values are Fussell-Vesely importance (FV Imp), Risk Decrease Factor (RDF), Fractional Contribution (FC), Risk Increase Factor (RIF) and Sensitivity Value for each Basic or Undeveloped Event.

Example of FTA Importance and Sensitivity Analysis report

Fault Tree Analysis is acknowledged as a key tool for increasing safety. It is unique and indispensable in analyzing risks and determining various combinations of hardware, software, and human error failures that result in a specified risk or system failure. Fault tree analysis is useful both in designing new products/services and in dealing with identified problems in existing products/services. In the quality planning process, the analysis can be used to optimize process features and goals and to design for critical factors and human error. As part of process improvement, it can be used to help identify root causes of trouble and to design remedies and countermeasures.

FTA is used by other RAM Commander modules - the Safety Assessment Software Module (compatible with aviation safety requirements, SAE ARP4761 and other standards) and MMEL (Master Minimum Equipment List analysis for aviation industry).

Event Tree Analysis (ETA)                                                                                  

****See also LOGAN Fault & Event Tree Analysis  for an alternative
FT & ET Analysis Tool*****

Event Trees are one of the most widely used methods in system risk analysis. It is an inductive failure analysis performed to determine the consequences of single failure for the overall system risk or reliability. Event Tree Analysis uses similar logic and mathematics as Fault Tree Analysis, but the approach is different - FTA uses deductive approach (from system failure to it's reasons) and ETA uses the inductive approach (from basic failure to it's consequences). An event tree itself is a visual representation of single failure sequences, it's influence on other events and on the whole system.

Main window of the RAM Commander Event Tree Analysis Module

ETA Module Features
  User-friendly and convenient tree building interface (zoom, export to clipboard as metafile, print, etc.)
  Customizable graphical representation (diagram elements colors, styles etc.)
  Events Library
  Event Probability assessment models:
   o user-defined
   o calculated (repairable/unrepairable/constant mission time/periodical tests)
   o linked to product tree element
   o linked to FMECA Failure Mode, NHE or End Effect
   o linked to Fault Tree basic event
   o linked to Fault Tree gate or tree top event
  Different Event logic types:
   o Binary logic 
            - True/False 
            - Success/Failure
   o Multiple alternatives (for events where not only True/False or Success/Failure outcomes are considered)
  Different Event probability types
   o Equal event probabilities in all sequences
   o Different event probabilities in different sequences (conditional probabilities)


Safety Assessment - based on SAE  ARP4761                                                     

Safety Assessment Software is a comprehensive safety tool implementing the requirements and tasks of SAE ARP4761, MIL-STD-882 and other standards. It is integral part of RAM Commander Reliability and Safety toolkit. Defined and developed in cooperation with our AIRBUS customers, it allows to perform FHA (Functional Hazard Analysis), PHA (Preliminary Hazard Analysis), SSA (System Safety Assessment), PSA (Probabilistic Safety Assessment). RAM Commander FMECA and FTA modules form the basis of aircraft safety analysis.

The safety assessment process has fundamental importance in establishing appropriate safety objectives for the System Under Analysis (SUA) and determining that the implementation satisfies these objectives. The safety assessment process is iterative by nature; using RAM Commander to support all necessary iterations and to produce all required output is the easy, accurate and time-saving way to do the safety assessment.

RAM Commander Safety Assessment Software Module implements tasks of qualitative and quantitative safety assessment required during system development:
 Generation and verification of safety requirements;
 Identification of all relevant failure conditions;
 Consideration of all significant combinations of failures causing failure conditions;
 Generation of output reports starting from the stage of Functional Hazard Analysis (FHA/PHA) and ending by the System Safety Assessment (SSA) verifying that the design meets safety requirements. Reports are generated as MS Word documents using customizable MS Word templates.
 AFO (russian standard required by AR MAC) support
 System Hazard Assessment and O&SHA according to MIL-STD-882. Reports are generated as MS Word documents using customizable MS Word templates.

Master Minimum Equipment List (MMEL)                                                    

The Master Minimum Equipment List (MMEL) is a document which lists the equipment that may temporarily be inoperative, subject to certain conditions, whilst maintaining an acceptable level of safety as intended in the applicable documents. Each MMEL document is specific to an aircraft type.

MMEL analysis is required for all aircraft manufacturers to certify aircraft safety in different aviation authorities such as FAA, EASA etc.

RAM Commander integrated MMEL module supports Master Minimum Equipment List generation using Reliability, FMECA, FHA (Safety) and FTA modules results.

RAM Commander's MMEL module main features:
   Compliance with MMEL requirements
   Integration with aircraft Reliability and Safety analyses modules
   Candidate Item selection
   Calculation(s) of Expected Probability before and after failure
   Automatic identification of the next (first in flight) and second worst failures
   Reports generation:
     Standard MMEL: "Five Column Format" - presents the standard MMEL report
     Detailed Quantitative Analysis - presents results of analysis on which MMEL selection has been made

MMEL module provides several algorithms for MMEL candidate selection:
  Algorithm  based on JAA MMEL development guidelines
  Algorithm implementing RRJ - 95/75 guidelines
User may select appropriate algorithm for system analysis.

Below is an example of standard MMEL 5-column report as generated by RAM Commander:


Functional Packages:

  • 5 Standard Operating Reliability Prediction Methods
  • BOM Builder, Temperature Curves, Mission Profile, and Import Wizard
  • Full set of ready-to-print Reliability Reports
  • Enhanced Report Generator for user defined reports


  • 5 Standard Operating Reliability Prediction Methods
  • BOM Builder, Temperature Curves, Mission Profile, and  Import Wizard
  • User Defined Components Reliability Data Module
  • Full set of ready-to-print Reliability Reports
  • Enhanced Report Generator for user defined reports
  • Components Library Module (over 400k components)
  • RBD - Reliability Block Diagram


  • Maintainability Module (according to MIL-STD-472 Procedure 5A)
  • Built in libraries for Tasks, Times, STE, Skills, and Materials
  • Maintenance Engineering Report (MEA Report)
  • Maintenance Task Analysis Report
  • Full set of ready-to-print Reliability Reports
  • ILS Supprt Fields (user defined)
  • BOM Builder, Temperature Curves, Mission Profile & Import Wizard
  • Enhanced Report Generator for user defined reports
  • RCM/MSG-3 Module
  • FMECA Module


  • BOM Builder, and Import Wizard
  • FMECA (covering both Hardware & Functional) Module
  • Customizable FMECA Worksheet
  • FTA Module
  • FMECA Import/Export
  • Testability Module
  • Full set of FMECA & FTA ready-to-print Reports
  • Full set of ready-to-print Testability Reports including graphical trouble shooting, fault isolation, etc.
  • FMD-97 Library
  • Enhanced Report Generator for user defined reports


  • SSA supporting IEC 61508 (Safety Standard for Safety Instrumented Systems) and MIL-STD-882D (SHA, O&SHA), SAE, ARP 4754A, and ARP4761
  • Customizable FMECA Worksheet
  • FTA Module
  • RBD Module
  • Markov Chains Module
  • FMECA Import/Export
  • Full set of ready-to-print Safety Reports
  • Enhanced Report Generator for user defined reports


  • SSA & FHA according to SAE, ARP 4754A, ARP4761, and FAR 25 1309b
  • FTA including ready-to print reports
  • MSG-3 (System, Zonal, and Structural) including ready-to-print reports
  • MMEL including ready-to-print 5-column report
  • FMECA including ready-to-print FMECA reports, BOM Builder, and Import Wizard
  • Enhanced Report Generator for user defined reports
  • Report Template Utility for layout customization


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