Engineering Failures: Determining Fault and Responsibility

When a product fails, assigning blame to an engineer can be complex and multifaceted. This article explores the various factors and responsibilities involved in determining fault in engineering design failures, particularly focusing on the intricate layers of responsibility during the product lifecycle.

The Role of Different Engineers in Ensuring Product Reliability

In the event of a product failure, different engineers play distinct roles in verifying that the product meets its intended specifications. Design engineers focus on ensuring that the design meets the design intent and functional requirements. When a design specification consistently achieves the intended outcome, the design engineer is generally considered to be in the clear. However, if the design falls short, the responsibilities may extend to other engineers and processes.

Manufacturing engineers are responsible for the manufacturing process. If the manufacturing process consistently conforms to the design specification, the manufacturing engineer can be considered not at fault. However, if deviations occur, this can lead to questioning the integrity of the manufacturing process.

Quality engineers focus on ensuring that the measurement/inspection/verification process reliably detects any non-conformances that deviate from the design specification. If this process fails to detect these issues, the quality engineer may face scrutiny.

Complexity of Failures: The Swiss Cheese Model

While the above roles each have specific responsibilities, the complexity of failures often involves multiple layers of responsibility. For example, in a serious case such as an engine failure that nearly brought an A380 aircraft down, the failure may be attributed to a combination of issues at different stages of the product lifecycle.

The Swiss cheese model is a useful analogy for understanding complex failures. Just as “slits in a swiss cheese” can lead to a disastrous outcome, a series of small issues can combine to cause significant failures. This model helps to visualize the cumulative effect of multiple layers of risk.

Types of Failures and Blame Attribution

The type of failure can significantly influence the attribution of blame. Failures due to abuse of the product, such as using a bridge or aircraft outside of its design limits, are usually the responsibility of the user, not the designer. Designers must ensure that products are designed with built-in safety measures to mitigate such issues.

However, when a failure is a result of systemic issues, the responsibility may extend to the design team, manufacturing processes, and quality control. For instance, the Hyatt Regency walkway collapse case illustrates how a poor design, compounded by subsequent changes, led to a catastrophic failure. This highlights the importance of thorough design reviews and robust risk management processes.

Collective Responsibility and Design Teams

Most designs are the result of collaborative efforts by a team of engineers and experts from various departments. ISO-certified companies are required to document design reviews as part of their quality management systems. These reviews often involve team members from different disciplines, ensuring a holistic approach to design and quality.

Tools such as Failure Mode and Effects Analysis (FMEA) can be used to identify and mitigate potential risks in the design and manufacturing processes. The involvement of multiple perspectives can help in minimizing the likelihood of failures.

Thorough Root Cause Analysis

In the event of a product failure, the optimal action is to conduct a thorough Root Cause Analysis (RCA). The RCA should aim to identify the underlying causes of the failure. It is important to investigate whether the issue was a design defect, material issue, manufacturing defect, or misuse of the product.

Each of these areas plays a role in the product lifecycle, and their interconnections can provide insights into what went wrong and why. For example, a robust design incorporating safety measures can prevent user error, while carefully selected materials and manufacturing processes can ensure reliability.

In conclusion, while engineers play crucial roles in ensuring product reliability, determining fault in a product failure is often complex and multifaceted. A comprehensive approach, including thorough RCA and the involvement of a multidisciplinary team, is essential to understanding and mitigating the risks of engineering failures.