Help?System Level FMEA

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    Hi, folks,

    I have some difficulties in a system level FMEA analysis, and I truely appreciate helps from people with hands-on experience:

    Supposed I am doing a system FMEA for an automobil engine:

    1. I start at a schematic drawing of the engine system, which shows both the engine system interactions/interface with other systems (part A), and the internal subsystems of the engine (partB).
    2. then list down the functions of the both A and B.
    3. then we brainstorming the requirements of A and B.
    4. If we can list down the detailed requirements of A and B in step 3, it should be easy to identify the failure mode.

    Here are the problems:
    1. The leadership wants to treat the engine system as a black box and focus only on A, but not B, even though B subsystem is well defined. I am not sure whether this is correct?
    2. Identifying the functions of A is not a problem, but the team has difficulty in estbalishing the requirements of A, for example, the functions of the Controller is to ” control the front moving”, but it is hard to establish the requirement of the controller. So I inspire the team by Fault Tree Analysis(5 Why), then it ends up a lot of root causes at component level and a lot of root causes that are not design related. This is apprantly not the intention for System FMEA-which are supposed to identify root causes that do not meet customer requirements at system level.
    3. We did a customer requirement analysis, and we try to convert the customer requirements into technical requirement by using QFD, then those technical requirements are seems disconnected with function requriements in step 3.

    We are frustrated and questioning the true value of the S-FMEA. We truely appreciate help from experienced people. If you have a good example (not those example in text book like AIAG), pls send to us for reference at: [email protected]

    Thanks in advance and have a good day!



    Shermalie Suckling

    Hi Rich @SSG

    The date on your post is last year so not sure if this is an issue for you still…but for what it’s worth…

    I would suggest breaking down this problem into smaller chunks and taking a 2 phased approach, particularly given you’ve already done the work to develop your Boundary Diagrams this way – In phase 1, consider the engine as a black box and develop your S-FMEA to give you your system level controls – A P-diagram will help to identify interactions between the various sources of noise (e.g. other systems, environment, customer usage). In phase 2, run your D-FMEA at a sub-system and component level…

    I stopped working in design a few years ago so don’t have anything I could send you, but have a look around on this site – there are some reasonable examples of P diagrams etc…Or have a look on the SAE website (…good luck

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