Are We Willing to Hear What “Failure” Has to Say?

Root Cause Analysis (RCA) is a useful tool for trouble shooting breakdowns and efficiently coming to a solution. I propose the following seven points for successful implementation of RCA that will naturally result in increased profits.

Semiconductor devices are almost always part of a larger, more complex piece of electronic equipment. These devices operate in concert with other circuit elements and are subject to system, subsystem and environmental influences. When equipment fails in the field or on the shop floor, technicians usually begin their evaluations with the unit's smallest, most easily replaceable module or subsystem. The subsystem is then sent to a lab, where technicians troubleshoot the problem to an individual component, which is then removed--often with less-than-controlled thermal, mechanical and electrical stresses--and submitted to a laboratory for analysis. Although this isn't the optimal failure analysis path, it is generally what actually happens.

This paper presents an overview of an integrated process for system maintenance, fault diagnosis and support. The solution is based on Qualtech System, Inc.’s (QSI’s) TEAMS toolset for integrated diagnostics and involves several key innovations. As a showcase of the integrated solution, QSI, along with Antech Systems and Carnegie Mellon University (CMU), have recently completed a research project for the Information Technology Branch at the Naval Air Warfare Center–Aircraft Division (NAWC-AD) in St. Inigoes, MD. The entire system, termed ADAPTS (Adaptive Diagnostic And Personalized Technical Support), provides a comprehensive solution to integrated maintenance and training.

Lately, I’ve been asked to provide root-cause analysis training more than ever before in my 14 years as an independent quality/lean consultant. This is interesting in the age of Six Sigma, especially because “analyze” is the heart of DMAIC (define, measure, analyze, improve, control). I find this interesting in this age of lean, in which the lean tools that are taught to so many people are only possible solutions to good root-cause analysis. I began to wonder, “Why does root-cause analysis suck?,” and I came up with the following possible root causes. You decide which apply to your company by asking “Why?” somewhere around five times until you find the systemic reason(s) that it sucks at your company. Drum roll, please . . .

What Causes Fatigue Failure? Metal fatigue is caused by repeated cycling of the load. It is a progressive localized damage due to fluctuating stresses and strains on the material. Metal fatigue cracks initiate and propagate in regions where the strain is most severe. The process of fatigue consists of three stages.

A fault tree is constructed starting with the final failure and progressively tracing each cause that led to the previous cause. This continues till the trail can be traced back no further. Each result of a cause must clearly flow from its predecessor (the one before it). If it is clear that a step is missing between causes it is added in and evidence looked for to support its presence. Below is a sample fault tree for the moral story of the kingdom lost because of a missing horseshoe nail.