reliability monitoring and traceability

[joshi]

For A Complex Systemlike An Aircraft How Can Reliability Of Systems,sub-systems Be Traceable Including Mechanical/pneumatic/hydraulic Systems.i Mean Right From Raw Material Stage, In-process, Environmental Tests, Functional Checks Etc. I Mean When Failure Data,failure Rate, Time To Failure Etc Is Not Available/data Confidence Level Is Low

[Arai.M]

Often complex systems that are repairable, are analyzed using a reliability growth program. For more information see http://www.weibull.com/relgrowthwebcontents.htm#Introduction. In this type of analysis, individual component data is not required but the analysis is done at the system level.
Regards,
Arai

[joshi]

Thanks Mr Arai, I am using Reliasoft's RGA Standard, however, i would like to submit my query again to you : '' Background: There are many vendors who manufacture many complex sub-systems/components, raw material testing, inspection/qc, six sigma analysis modified for critical parameters(limited samples) and system testing - acceptance & qualification. What is available is test result :Sample size 2, no failures, minor waivers were accorded. How does one monitor reliability right fron design stage. No field data is available; being a developmental product. Use of process flow diagrams/checksheets, vendor's inwards good inspection control etc can lead to a high quality so as to achieve inherent Reliability, however, once production commences how does one ensure monitoring of Reliability be it in terms of time to failure, number of failure, availability etc. ?

[Adamantios]

Joshi...If I understand your question, you are asking about traceability of actions, and reliability monitoring. My answer to this is using a FRACAS or FMEA database. With a Failure Reporting And Corrective Action System, you can record all the different pieces of information that you have about the system and its subsystems/components, as well as the different actions taken during development and beyond. Once in the field, data can be collected and stored in the FRACAS which can then be used for statistical analyses.

Another approach is using FMEAs. Potential failures are pointed out, and actions, test results, vendor actions, etc. are recorded. Of course to achieve this you will need something more than Excel to do your FMEAs, and particularly you will need a package that uses a relational database.

In my opinion both the FRACAS and FMEA systems are necessary since they complement each other, but you can achieve a certain level of monitoring and traceability with either one. For example, an FMEA database allows you to enter potential failure modes, but cannot be used as a data collection system. In FRACAS you record only failures seeing, but it is a data collection system which you can extract data from and perform statistical analyses.