Non-Component Failure Modes in Failure Mapping

There is an old saying that the most unsafe component in a vehicle is the “nut behind the wheel”. This saying is intended to highlight the fact that most vehicles have been designed and manufactured in a manner that, if operated correctly, will be safe. Many aspects of reliability are very similar. For many physical systems, the original design and construction has produced a system that adequately addresses most of the issues that would lead to poor reliability … as long as they are operated and maintained correctly.

When reliability failures occur, diagnostics and troubleshooting typically identify a specific physical component that has deteriorated in some way and needs to be replaced. Once replaced, the device function can be resumed. In some cases, the system has been operated and maintained correctly and the failure is the result of an inherent weakness of the component that was replaced. In other cases, the system was improperly operated or poorly maintained.

A comprehensive Failure Mapping based reliability program will identify the Failure Mode in terms of the component that was replaced and its condition. Investigation will go a step further and identify the Failure Mechanism (e.g. corrosion, erosion, fatigue or overload). A truly complete reliability program will go a step further and perform Root Cause Analysis and identify the Physical cause, Human cause and Systemic cause.

Unfortunately, many reliability programs have neither the time nor the human resources needed to perform Root Cause Analysis on many of the failures that are handled on a day-to-day basis.

On the other hand, some systems do have the ability to quickly identify situations when the failure has been caused by the “nut behind the wheel” (operator) or the “nut that turns the wrench” (maintainer). It is often possible to tell from record or other information sources (e.g. dates on filters) that required maintenance has been ignored. It is also frequently possible to tell from records or other information when the failure resulted from poor operation (e.g. running a pump dry or blocked in or operating beyond the rated capacity).

In these cases, the effectiveness and efficiency of the problem solving capabilities within the Failure Mapping system will be enhanced by including selectable Failure Modes pointing directly at misoperation or inadequate maintenance. For instance, if a component has worn beyond the acceptable limit because it was not replaced at the appropriate time, a more descriptive failure mode than “Bearing – Worn” would be “Bearing – Unmaintained”. If a pump has failed because it was started remotely while still blocked in, rather than “Bearings – Melted” a better Failure Mode would be “Bearings – Damaged by Misoperation”.
In either case, this subtle change would allow more effective and efficient use of resources and correction of problems.

This article introduced the following concepts:

- Failure Modes that are not attributable to physical components.

- Failure Modes attributable to the human factor.

- How best to track these failures in a Failure Mapping environment.

If readers would like to comment on these or other closely related subjects, they are invited to do so.