Human error in maintenance

Below are excerts from article entitled "human error is preventable" by Daryl Mather. Published at the plant.com website in April 2007

Human error used to be an area that was only associated with high-risk industries like aviation, rail, petrochemical and the nuclear industry. The high consequences of failure in these industries meant that there was a real obligation on companies to try to reduce the likelihood of all failure causes, not just those related to “normal” or engineering failures. However, there is a lot to be gained, for relatively little outlay, by including a focus on human error within all maintenance operations.

Human error continues to be a common cause of asset failure, both in terms of how an asset is maintained, as well as how it is operated. We see this all the time in areas such as poor calibration, poor alignment, incorrect settings, and even poor quality workmanship.

If you look at the conditions involved in asset maintenance, there are a multitude of reasons why human error would occur which include frequent removal and replacement of large numbers of varied components, often carried out in cramped and poorly lit spaces with less-than-adequate tools, and usually under severe time pressure.

Equipment alignment is a prime example. Fixing a motor to a new plinth and then aligning it to whatever it is driving is a pretty standard task. Yet there are a large number of ways we can make mistakes. Poorly marking the footing mounts, poor drilling (too shallow, not in line) and poor alignment practices are all valid examples.

Also, after a few months new concrete plinths have a tendency to “settle,” often forcing misalignment through shifting of the motor. Failure to take this into account and to perform the necessary checks to correct it if it occurs, is also a human error related issue.

You’ll be surprised to learn that the work procedure helps to increase the likelihood of error, not reduce it. For example:

* Very wordy sentences and instructions will often be ignored. This is human nature. Make sure that the instructions are broken into logical parts, and that they are written in short concise sentences in layman’s terms.
* Studies have shown that when there is a long list of instructions, those in the middle will often be omitted. Make a quality assurance check at the end and ask the technician to double check whether they did certain frequently omitted tasks.
* Too many instructions will be ignored, as will too few. Procedures need to be aimed at presenting an accurate level of detail and instruction as is required.
* A lot of work instructions are focused on the present, but often there is a need for a re-check of alignment several months afterwards. Employ this in the work procedure; make it a task for the maintenance scheduler or to program a separate task once this task has been done.
* More than all of the above, procedures must not tell technicians how to perform basic skills, or they will be ignored. (E.g. don’t go into detail about how to torque a bolt or remove a screw.)

Procedures is one of the many areas where slight adjustments in current practice could have a big impact in reducing lost time and money due to human error. There are many others.