Failure modes and symptoms: the House M.D. approach to inspection and lubrication programs

Whether your job is to maintain an airplane, a car or a paper machine, reliability stands as a pillar of sustainable success. The efficiency, safety, and longevity of industrial assets depend heavily on the effectiveness of maintenance strategies.

However, achieving excellence in maintenance requires more than just reactive fixes and routine checks. It necessitates a comprehensive understanding of failure modes and their integration into the very foundation of maintenance practices.

1. Ineffective and inefficient PMs

Efficient and effective preventative maintenance programs are essential for ensuring optimal equipment reliability and performance in industrial settings. However, certain signs can indicate inefficiency and ineffectiveness in these programs, pointing to areas needing improvement. Here are some key indicators to watch out for: 

  • Frequent breakdowns despite regular PM. 
  • Persistent unplanned downtime in critical assets. 
  • Escalating maintenance costs without improved reliability. 
  • Reactive maintenance dominates proactive efforts. 
  • Lack of data-driven decision-making in maintenance. 
  • Limited use of condition monitoring technologies. 
  • Inconsistent compliance with maintenance schedules. 
  • Poor documentation of maintenance activities. 
  • Insufficient stakeholder engagement in maintenance processes. 
  • Failure to learn from past failures to prevent recurrence. 

Recognizing these signs early can help organizations take proactive steps to enhance their preventative maintenance programs and take them out of the catch-22 reactive loop: 

2. What are failure modes? 

Failure modes, in essence, are the different ways in which a component or system can fail. They encompass a spectrum of potential malfunctions, from gradual deterioration to sudden breakdowns, each with its unique causes and consequences. Recognizing and analyzing these failure modes are paramount for crafting proactive maintenance strategies that mitigate risks, optimize performance, and minimize downtime. 

Example : overheat is a failure mode than can apply to a sick human, as well as a misfunctioning machine: 

Looking at the pictures above, we don’t know why a person/machine would overheat (cause), we are simply observing a symptom (state) and are aware that it could result in hospitalization/failure (consequence) if not dealt with in time. 

For those of you who watched House M.D., you may be familiar with his methodology of differential diagnosis: focus on the symptoms and cross-reference them to find the right cure. 

So it’s simple: in order to properly troubleshoot issues on a piece of machinery, symptoms must be clearly identified.

3. Look for symptoms! 

Based on our experience, it is not uncommon to have PM rounds that include tasks such as “inspect motor”, “inspect pump”, “grease bearing”, etc. These are too subjective tasks and do not bring enough value to the inspection process. Worse, they deprive younger or newer workers of important information about the PM they are about to execute. 

Case-study : this is a real monthly inspection we encountered a few years ago. It is supposed to address a critical lubricating system on a steel laminator, done while the asset is operating: 

OKCorrected To repair What’s wrong with this PM? 
Motor (state)    Too subjective, what does it mean? 
Pump (state and noise)    Ok for “noise” but the rest is subjective, like the motor 
Coupling (state and play)    How are you supposed to check the state and the play
of a coupling with a visual inspection while the asset is in operation? 
Hoses    What about them? What do I have to check? 

After the example above, it becomes apparent that by identifying the potential ways in which equipment shows upcoming failure indications, maintenance professionals can develop targeted monitoring techniques and diagnostic protocols, using visual inspection or predictive technologies such as vibration analysis, thermography, and oil analysis. These tools enable early detection of anomalies, allowing maintenance teams to intervene proactively, often before a failure escalates into a full-blown breakdown.

4. How to go further? 

Never hesitate to include the following in your PM documents 

  • Pictures of what to look for. Include arrows, or circle areas where the technician should focus 
  • Measurements : pressure, temperature, torque, thickness, deflection, you name it! Also, indicate min/max or targeted values (expected torque value for bolts for example) 
  • Instructions : they can be listed as sub-tasks or be a linked detailed procedure 
  • Lubricants 
  • Tools necessary 

Example of a failure modes-based inspection round 

In conclusion, by categorizing failure modes based on their severity, likelihood, and detectability, organizations can tailor maintenance plans to suit specific equipment and operational contexts. Furthermore, integrating failure mode analysis into the broader framework of reliability engineering fosters a culture of continuous improvement. By documenting and analyzing failure events, organizations can identify patterns, root causes, and systemic weaknesses, facilitating iterative enhancements to maintenance practices, design specifications, and operational procedures. This proactive approach not only enhances asset reliability but also drives efficiency gains and cost savings over the long term. 

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