[SystemSafety] Functional hazard analysis, does it work?

[paul_e.bennett at topmail.co.uk]

On 19/01/2016 at 12:42 AM, "Matthew Squair" <mattsquair at gmail.com> wrote:
>
>A question to the list.
>
>Does the process of functional hazard analysis 'work' in terms of
>identifying all functional hazards that we are, or should be, 
>interested
>in?
>
>The way the FHA process is defined in the various standards seems 
>IMO to be
>very reductionist in nature, fine for identifying the specific 
>consequences
>of a single functional failure mode, but what about functional
>interactions, multiple functional failures, the interaction of 
>modes with
>functions and so on.

Your impressions are correct in that just doing FHA would focus too much 
on just the hazards associated with the functionality. In a full HAZOP to 
identify the hazards that must be addressed, you also need to consider a
range of risks associated with the operational environment, the personnel 
of all types who will interact with the system (and their tasks) and a number
of potential natural hazards that may occur. My HAZOP kick-off check-list is
5 pages long which can prompt us to ask the right sort of questions. It was 
initially listed in Def-Std 00-55 or 00-56 but I have added a few more to it 
since adopting it as a starting point about 20 years ago.

>The background to this is that the project I'm working with is 
>about to
>commit to a significant campaign of 'FHA'-ing. So we're engaged in 
>a little
>bit of professional navel gazing about the efficacy of the 
>technique before
>we commit to the campaign.

Just don't let them rely on the FHA alone. It is a useful sub section of a full
HAZOP but you need to explore a much wider scope than the hazards posed 
by the functionality alone.

>-- 
>*Matthew Squair*
>
>
>BEng (Mech) MSysEng
>MIEAust CPEng
>
>Mob: +61 488770655
>Email: MattSquair at gmail.com
>Website: www.criticaluncertainties.com 
><http://criticaluncertainties.com/>

Regards

Paul E. Bennett IEng MIET
Systems Engineer

-- 
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Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett@topmail.co.uk>
Forth based HIDECS Consultancy.............<http://www.hidecs.co.uk>
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