WHERE DO WE REALLY COME FROM?
To computer based maintenance over time
The history and current state of maintenance
Tools and machines have been used for a long time by humans to simplify daily routines. Think about spears for hunting in the bronze age or using simple cranes to construct monumental buildings like the Colosseum in ancient Rome. During all this time these tools were only repaired when they broke. Maintenance was non-existent. Over time this changed.
Maintenance is now an important part of daily routines in all industries and modes of transport. Companies today are aware of the fact that proper maintenance of machinery reduces costs and increases longevity. In the long run, adequate maintenance ensures quality production and transport.
Over the years, maintenance methods have evolved in virtually all industries. Modern methods have been tailor made to the specific needs of each industry. At the same time, if you take a step back and look the bigger picture of many maintenance systems, it becomes clear that most of the systems in use are based on similar principles. The following paragraphs briefly outline these basic maintenance strategies, how they evolved over time and what changes you can expect in the future.
Maintenance before the 1950s
The initial turning point in maintenance history was marked by the end of the second World War. This war triggered a lot of technological advancements such as the jet engine which forced engineers to reconsider their maintenance approaches.
Before World War II, machinery was quite simple and carefully engineered which made it very reliable. Consequently, there was no need for daily maintenance. Maintenance was only performed when a failure was detected. This maintenance approach was called Break-Down-Maintenance (BDM) or Corrective Maintenance (CM). Due to the nature of this maintenance method, no factory personnel were dedicated specifically to equipment maintenance. Defective parts were often replaced by workers only when dysfunction appeared. As a result, long production delays due to missing spare parts were quite common yet unpredictable, disturbing production and delivery schedules. This maintenance approach was very simple and cheap, but in the long run, highly ineffective as it caused unexpected production delays and cost companies a lot of money.
In the mid 40s, machinery became more complex. Driven by the war, there were many technological advancements in a very short time. The aviation industry in particular saw many changes caused by the development of the jet engine. Based on this new technology, a whole new generation of airplanes was developed for commercial aviation. These new airplanes were far more complex than those being used before the war. With the increasing complexity of equipment, more and more malfunctions occurred and more repair work had to be done.
The industry reacted and introduced new forms of maintenance methods that rendered BDM nearly obsolete. Today, BDM is hardly used anymore.
Maintenance from the 1950s to present
Confronted with more complex machinery, engineers had to develop new methods to maintain the equipment and make it more reliable. This led to the development of a process called Preventive Maintenance (PM) which is still used by many industries today.
PM is probably the most common maintenance method today. With preventive maintenance, all maintenance jobs follow a fixed schedule, typically created by the equipment manufacturer. Suggested maintenance intervals are usually based on time (e.g. every two weeks) or running hours (e.g. every 50 hours). Intervals based on fuel consumption, for example, are far less common.
Following a fixed maintenance schedule greatly extends the equipment lifespan, minimizes unexpected malfunctions and reduces production delays.
The downsides of preventive maintenance are high. Sometimes this includes unnecessary costs and large amounts of time that must be invested to cover all maintenance work. Parts such as gaskets are often exchanged during routine maintenance even if they are not worn.
Despite these disadvantages, PM helps to keep machinery (yachts included) in good and safe condition and outweighs the invested time and costs by far compared to doing no PM at all.
The disadvantages mentioned above regarding added labor time and costs involved were the reasons why the aviation industry started searching for different way to perform maintenance in the 1950s.
Maintenance driven by the aviation industry
Shortly after preventive maintenance was introduced to the aviation industry, airplane manufacturers realized that this maintenance method was not sufficient. The industry had high hopes to reduce equipment failure by a large margin using this new process. However, in contrast to other industries where preventive maintenance had a big impact, aviation companies did not observe a significant decrease of equipment failure, even though they spent much more time on maintenance and exchanging parts which resulted in higher costs for airplane maintenance. As a result, aviation companies, frustrated by ongoing equipment failures, analysed maintenance records in the 1960s to find reasons for this. The results were astonishing. Contrary to the assumption that more failures occur with greater age of parts, researchers found that failures appeared randomly over time. They realized that they had to change their maintenance approach to reduce equipment failure. They developed a methodology based on several equipment factors e.g. reliability characteristics, impact of failure and operating environment to name a few. That is why this method was called Reliability Centered Maintenance (RCM).
Measures were taken on the basis of this data analysis resulting in a massively reduced number of maintenance jobs without increasing risk of failure of equipment. The impact of this new maintenance approach can be illustrated by the comparison of the Boeing DC-8 and 747-100. The old Boeing DC-8 being maintained following traditional PM needed roughly 4.000.000 labour hours before reaching 20.000 operating hours. The more complex 747-100 following RCM only needed 66.000 labour hours to reach the same operating hours.
As you can see the impact of this new approach in preventive maintenance in the aviation industry was immense, along with its methodology regarding maintenance schedules, reducing failure rates and maintenance costs drastically. That is why the US Department of Defense’s attention was drawn to this methodology. The DoD helped to improve and standardize RCM in the following years and started to use it in all divisions of the armed forces. Today the term RCM is protected and owned by the Aladon Network.
Closely related to RCM is Risk Based Inspection (RBI). This method is very similar to RCM. It combines the concept of failure identification and risk evaluation to create a maintenance program suitable for a complete system such as a ship or an oil rig.
Although being very effective maintenance methods, both RCM and RBI need a lot of data and initial work to turn them into an effective preventive maintenance program for a technical system such as an airplane or a navy vessel. During the setup process, a dedicated team will have to work full time on this topic and follow a standardized process. This is why both concepts are most commonly used in complex environments with high safety standards.
The methods described above, PM, RCM and RBI, are the current state of modern maintenance, but new maintenance methods are already being introduced and used.
The future of maintenance
In recent years there were several technological advancements that introduced the opportunity to develop new kinds of maintenance approaches. First of all, processing power in modern computers has increased greatly in the last 10 to 15 years. This progress made it possible to introduce new technologies such as machine learning to the broad mass of users. Other important drivers for new maintenance systems are the miniaturization and price reduction of sensors and the possibility of sensors to communicate with other sensors and systems (Internet of Things, IoT).
Based on these new technologies, Condition Monitoring (CM) / Predictive Maintenance find their way into all kinds of different industries, e.g. commercial shipping and aviation).
CM is constantly monitoring the condition of machinery with the goal of finding defects and identifying the root cause of failure. The collected data is compared to reference values for the equipment, for example, an optimal working temperature range for an engine. If the system detects deviations from this specified range, it triggers pre-defined maintenance tasks (e.g. visual inspections, part changes etc.) best fitted to the collected values. Machine learning helps to make this process more accurate and reliable over time. The more data that is collected, the better the maintenance.
The role of PMS systems in modern maintenance
Modern PMS systems like IDEA Yacht support users to maintain equipment in several ways and help to keep a vessel safe at all times.
Maintenance information can be put into the PMS system and tasks can be triggered when certain time based intervals, hour counter based intervals and/or certain conditions are being reached. Crew members are informed about the upcoming tasks and all the work that has been done is documented to help later on in potential investigations or audits.
The constant improvement of PMS systems ensures that a variety of maintenance methodologies including CM can be used on board.
Daniel Wolthausen (Dipl.-Wirt.-Ing.(FH) & MSc)
IDEA Product Manager