Risk-based thinking is a current mantra in Quality Assurance circles. Whereas in the past we may have followed more formulaic methods to meet technical and customer requirements, we now have to venture into a less defined regime of “risk”. Risk is harder to identify than a specified attribute or quantifiable measure. As a mortal animal, risk has psychological associations with physical hurt and survival instincts. Risk is an abstract concept but we are usually advised to avoid it for fear of losing physical or mental wellbeing. But throughout our lives and our work activities, the shadow of risk always falls, ever present, waiting to tap on our shoulder and ruin our plans. So the wise will acknowledge this unwelcome companion and instead of ignoring the shadow, try to shed some light and understand it better.

A standard which facilitates a better understanding of risk is AS13004 Process Failure Mode Effect Analysis (PFMEA) and Control Plans. PFMEA is a technique which structures our analysis of the risks associated with any process. If it is a design process, this is renamed as Design Failure Mode Effect Analysis (DFMEA). The technique is generalised by the initials FMEA, encompassing both the above applications. FMEA is a technique by which each possible mode of failure is considered in turn, and the risk that it presents. The assessment of risk is done by scoring three factors for that failure mode; the severity of the impact if it does occur, the likelihood that the failure will occur, then the likelihood of detection by process control. The standard provides guidance as to how each factor should be scored between one (best case) and ten (the worst case). The three factors are then multiplied together to provide a Risk Priority Number (RPN) for the process. A high RPN indicates a high risk and therefore a focus for process improvement. Some organizations will set a threshold RPN which all processes must not exceed. AS13004 is a thirty-page standard with case studies for illustration, templates for documents to be completed during the assessments, and guidance notes.

Although the AS13004 standard may look quite complex, it is formalising a process that all of us use in daily decision-making. As an example, our decision of at what time to leave for work may be based upon an assessment of the severity of consequences of being late, the likelihood that a delay will occur, and the likelihood that we can detect the delay in time to divert to an alternative route. Even though we don’t calculate a Risk Priority Number, we do modify our process according to this mental assessment. For example, if we have an important meeting early at the beginning of the day, we set-off earlier. Or we may choose a route that permits us to divert if required and not become stuck in a traffic jam. AS13004 lets the user apply the same logic to manufacturing processes and to be more precise and accountable for the resulting decisions.

This standard is produced by an SAE committee for Aerospace Engine Supplier Quality (AESQ) and is available from the SAE Mobilus website. Although primarily targeted at aircraft engine part suppliers, it is a useable standard in any industry sector. This committee also produces the AS13000 Problem-Solving Requirements for Suppliers and several associated standards linking risk assessment, problem solving, variation management and process control. AS13000 uses the 8D technique, developed in the Ford Motor company and now refined for use in aircraft engine manufacturing. FMEA can be used as one of the assessment tools within the 8D technique. The AS13004 standard also supports AS9100 Quality Management System Requirements for Aviation, Space and Defence Organisations. And it also accords with AS9145 Requirements for the Advanced Product Quality Planning and Production Part Approval Process (PPAP)

SAE AS13004 defines the role of PFMEA in the Quality System using this process map:

The AS13004 standard gives the user an objective way of assessing risks in a process, which permits the eradication or mitigation of such risks by use of this and the associated standards.

For questions contact paul@mfn.li

Standards Forum
by Paul Huyton,
MFN Course Director World Wide
more information at www.mfn.li/trainers