New Standards to enhance dependability

Managing risks and making systems and product perform more reliably

By Morand Fachot

Dependability, the “ability to perform as and when required”, applies to any physical item such as a system, product, process or service. It is now central to our lives as it is difficult to imagine a world where things do not work as expected. IEC Technical Committee (TC) 56: Dependability has recently published two additional International Standards that will contribute to enhance dependability.

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Using past failures and incidents to manage future risks

Analysing the causes of failures or incidents affecting systems, products or processes is the goal of root cause analysis (RCA). Using RCA may help prevent future design, production and operation errors (or on the contrary strengthen positive features), and as such play an important role in risk assessment and management.1

IEC 62740:2015, Root cause analysis (RCA), describes the basic principles of RCA and specifies the steps that a process for RCA should include. This standard identifies a number of attributes for RCA techniques which assist with the selection of an appropriate technique. It describes each technique and its relative strengths and weaknesses.

Causes for failures vary in nature, including design processes and techniques, organizational characteristics, human aspects and external events.

RCA can be used for investigating the causes of non-conformances in quality (and other) management systems as well as for failure analysis, for example in maintenance or equipment testing.

The intent of this standard is to describe a process for performing RCA and to explain the techniques for identifying root causes, such, for instance, as the method known as the "5 whys". Where a why question provides several causal factors, each is explored and the method produces a why tree.

The why method is used alone for simple situations but is also inherent in more complex tree methods. IEC 62740 states that the 'why method' "can be useful for eliciting information from witnesses on how and why an event occurred because the simple question ‘why’ does not make assumptions about cause or lead the witness".

Assigning responsibility or liability is outside the scope of this standard.

Setting requirements

IEC 62741:2015, Demonstration of dependability requirements – The dependability case,
gives guidance on the content and application of a dependability case. A dependability case is an evidence-based, reasoned, traceable argument created to support the contention that a defined system does and/or will satisfy the dependability requirements.

The standard establishes general principles for the preparation of a dependability case and offers background outlining the principles and purpose of a dependability case. It notes that it provides a reasoned and traceable argument based on evidence that a system satisfies the requirements and will continue to do so over time. It demonstrates why certain activities have been undertaken and how they can be judged to be successful.

IEC 62741 lists principles of the dependability case, such as description, making claims and using evidence in the dependability case. It gives too the evidence framework and details of the procedure to prepare a dependability case report.

The standard also describes the development of a dependability case from general features and preparation to various stages that include concept, development, realization, utilization and more.

This standard is intended as guidance, it states that its "guidelines are not prescriptive in nature, they are generic, they should be tailored to the specific objectives and are not exhaustive".

Both standards will join the 55 previously developed by TC 56 to make a significant contribution to improved dependability of systems, products, processes and services.

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