SOR 521 Rules

Abstract

Chris discusses ‘rules’ – rules we need to apply and rules we must bend. Rules can range from traditional practices and procedures through to the laws of nature. But we as reliability engineers need to know which of these rules we must adhere to, and which are our duty to try and bend. Want to learn more? Listen to this podcast!

Key Points

Join Chris as he discusses ‘rules.’ Rules we need to apply and rules we must bend. Rules can be anything. Something a textbook tells us to do. Or a standards document. Or direction from a senior practitioner – like a rule of thumb. Nuggets of gold. Then there are the rules associated with the laws of physics. A fancy name for rules. But we should only follow certain unalienable rules. Rules like the laws of nature, physics, and statistics. They change for no one. But if we are trying to develop something new and exciting, then the rules that used to apply may not be helpful anymore. In fact, they may give us a false sense that we have a reliable product.

Topics include:

Rule #1 – the ‘laws’ of statistics and physics (can’t bend). Le’ts say we get test results where most of the data is ‘good.’ Most of our prototypes survived until the end of our reliability demonstration test. But a certain number failed to survive until the end of our test – which puts our developmental milestone in jeopardy. What do we do? Call these few data points that will get in the way of progress as ‘outliers’? Things that don’t count? The clear answer is we clearly shouldn’t. But we often can’t help ourselves. We look at the failures in greater detail and try to discredit them. Our customers will never use them in that way. That defect won’t be present once our manufacturing process is more mature. We can design that issue out before our final production prototype and so on. And before long … we have convinced ourselves that the laws of large numbers and physics shouldn’t apply.
Rule #2 – the ways we have always done something (should bend). I have worked with the satellite industry. And satellites need to follow processes and procedures described in guidebooks, standards, traditional qualification tests and so on. All these rules tend to focus on wear-out failure mechanisms and modes. But – every academic study to date has shown that satellites suffer from wear-in or infant mortality failures. This makes sense – most satellites are ‘one-offs’ or made on very small production runs. Unfortunately, so much time and money are focused on following the rules that make us focus on wear-out failures only. And the processes and procedures aren’t changing any time soon. Why? Because it is easy to keep doing the same thing that everyone else has done and get that sense of security.

I daresay you can think of many more examples! But the point is that we must focus on reliability. Rules are only helpful if they help us achieve reliability. This means we adhere to the laws of physics, but don’t mindlessly do the same thing we have been doing for the last 10 years.

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