Preventive Maintenance: A Guide

Preventive maintenance are routine procedures that help reduce equipment failure and unplanned downtime.

Preventive maintenance includes routine procedures like inspections, lubrication, and belt adjustments. In addition to manual equipment upkeep, preventive maintenance also includes the careful planning, scheduling, and record keeping of past inspections and service reports.

Companies that regularly use heavy machinery implement preventive maintenance procedures in order to avoid equipment failure and to maximize efficiency. Preventive maintenance is used in industries like oil and gas, manufacturing, mining, and more.

What Is Preventive Maintenance?

Preventive maintenance refers to any routine maintenance performed at regularly scheduled intervals to reduce the likelihood of equipment failure, including inspections, cleanings, part replacements, and machine repairs.

The goal of preventive maintenance is to ensure that a piece of equipment or machinery continues to function as the manufacturer intended. Preventive maintenance plans also minimize workplace injury, prevent unplanned downtime, and help reduce the cost of any repairs.

The Elios 3 inspecting a water management system

Why Is Preventive Maintenance Important?

Preventive maintenance can bring a number of benefits to a company, many of which increase efficiency and cut costs. Benefits include decreased equipment downtime, increased worker safety, and regulatory compliance.

The price of preventive maintenance is almost always less than that of reactive maintenance, which only deals with an issue or equipment failure after it's happened. Reactive maintenance, or run to failure (RTF) maintenance, tends to result in high costs and increased downtime. 

Checking equipment at regular intervals prevents mechanical failure instead of when it crashes allows companies to be proactive rather than reactive.

When making budgeting decisions for the future year, preventive maintenance can be one key piece of a larger strategic budget framework, allowing you to create a wholistic plan that targets future goals for your organization.

Advantages of Preventive Maintenance

Preventive maintenance procedures are enacted in order to prevent issues from ever occurring in the first place.

Here’s a closer look at some of the reasons why preventive maintenance is so important. 

Minimizes Downtime

When machinery is operating as intended as a result of preventive maintenance, there is a reduced chance of unplanned downtime affecting the company in a negative way. 

Equipment downtime can be incredibly expensive for a company, especially if it is unplanned or the result of an emergency. In fact, according to a report by Aberdeen Strategy and Research, unplanned equipment downtime that interrupts production can cost a company an average of  $260,000 per hour in revenue. 

In addition to being costly, unplanned downtime can also strain relationships with clients, which may result in a further loss of profit later on down the line.

While it is sometimes unavoidable, proper preventive maintenance measures help ensure that equipment downtime is safe, scheduled, and unsurprising. 

Maximizes Equipment Lifespan

Preventive maintenance not only reduces the amount of downtime for a piece of machinery—it also ensures that the equipment lasts. 

When equipment is routinely inspected or serviced, the asset’s overall longevity is greater. This reduces the amount of resources that are wasted and ensures that all equipment gets its full use before being retired.

By maximizing equipment lifespan through a preventive maintenance schedule, companies can delay the need to buy new machinery, which frees up the budget for other areas of the business that may need it more.

An inspector recording the operation of oil and gas process

Helps Keep Workers Safe 

When assets are operating in the way that the manufacturer intends, employees are safer by default. Preventive maintenance ensures the normal operation of assets, reduces equipment failure, and reduces workplace accidents.

Equipment that is not regularly serviced by preventive maintenance techniques can fail in a number of catastrophic ways, and the list of workplace injuries that can occur is exhaustive. 

In this way then, preventive maintenance can keep workers as safe as possible and, in some situations, even save lives. Fewer workplace accidents also means lower insurance and workers’ compensation costs.   

Lastly, preventive maintenance is far safer than other maintenance solutions like RTF maintenance. If an asset runs until it breaks, it is infinitely more dangerous for a worker to be exposed to that danger than it would be for the same worker to have performed a scheduled preventive task earlier in time.

Helps Ensure Regulatory Compliance 

Most industries have regulatory standards for performing preventive maintenance on assets. If standards are not met, companies can be fined or face other penalties.

Having regularly scheduled preventive maintenance ensures compliance and prevents companies from being fined. By ensuring that all machinery is operating as it should, companies will meet their regulatory board’s compliance. 

Limitations of Preventive Maintenance

For the greatest effect, preventive maintenance should be implemented alongside a broad and wide-reaching maintenance framework that is focused on worker safety and the avoidance of equipment failure. 

Despite the following limitations, preventive maintenance is still one of the best maintenance plans for companies who want to extend the life of an asset.

Success Rate

Preventive maintenance can be used to reduce the chance of equipment failure, but it’s important to remember that reduction is not the same as elimination. While the best preventive maintenance plans limit failure, they do not account for accidents, natural disasters, or other situations that are difficult to account for.

Technological Constraints

While some assets have sensors and/or gauges that help prevent mechanical failure, other assets are only inspected and maintenance on a set schedule. 

Predictive maintenance, which uses complex calculations and algorithms to predict the point at which an asset will fail, is a more effective measure than what can be caught by preventive maintenance procedures.

Up Front Costs

While not nearly as expensive as reactive or predictive maintenance, there is an upfront cost to all preventive maintenance procedures. For smaller businesses and companies where budgets are tight, it may be difficult to fund all needed preventive maintenance practices, including planned downtimes.

Changing a car filter

Time Constraints

Preventive maintenance takes time. Sometimes, an asset will need to be completely turned off in order for the asset to be inspected or maintained, skewing production goals. It may also be difficult to find time to perform preventive maintenance tasks especially in companies where resources and workers are limited. 

Worker Limitations

Most preventive maintenance solutions will require an increase in staff or, at minimum, an increase in hours for current staff. Proper inspection and maintenance tasks require more resources.

Over Maintenance

Resources, time, and money could be wasted if a company’s preventive maintenance plan dedicates resources to precautions that are not needed. A preventive maintenance plan should be adjusted based on historical data, while still maintaining a regular schedule.

What Are the Types of Preventive Maintenance? 

There are three main types of preventive maintenance: 

• Time-based maintenance 

• Usage-based maintenance 

• Condition-based maintenance

Time-Based Maintenance

Time-based maintenance, or calendar-based maintenance, is a type of preventive maintenance that is completed at regularly scheduled intervals. This is one of the most common types of preventive maintenance. 

Changing the air filter in a climate controlled indoor space is a great example of time-based maintenance since it typically needs to be changed every three months.

Time based maintenance requirements usually come directly from the manufacturer, and can occur on the following timelines, depending on the asset: 

• Weekly

• Monthly

• Quarterly

• Yearly

Historical records are imperative to know which equipment needs special attention.

The primary disadvantage is that time-based practices will sometimes lead to over-maintenance. Consider a filter that, according to the manufacturer, needs to be replaced every three months. 

That may be accurate for an area that is highly trafficked or regularly used, but if the filter is in a warehouse or part of a factory that does not receive much traffic, changing the filter after three months may be a waste of time and money.

 Cleaning a condenser tube from a chiller

Usage-Based Maintenance

In usage-based maintenance, a machine or system’s usage statistics are used to trigger maintenance checks. Instead of relying on time, usage-based preventive maintenance focuses on how often a piece of equipment has actually been used. 

Usage statistics can include a number of measurements, including: 

• Cycle counts

• Miles/kilometers traveled

• Operating hours

• Runtime

A great example of usage-based maintenance would be preventive maintenance performed on an automobile after a certain distance is driven. Things like a tire rotation or a transmission check are usually performed under usage-based conditions. 

Usage-based preventive maintenance helps prevent over-maintenance by ensuring that machinery that is less used does not “steal” away resources from other equipment that may require more regular attention.

Condition-Based Maintenance

Condition-based preventive maintenance is dependent on monitoring the actual condition of an asset. Inspectors can use that data to determine when repairs and other maintenance need to take place.

Essentially, condition-based maintenance consists of intimate knowledge of how an asset performs, and noticing when maintenance is required. Performed properly, condition-based maintenance can be just as effective at stopping mechanical failure as all other forms of preventive maintenance. 

Signs of declining performance are typically the triggers for condition-based maintenance. This decline in performance can be observed through a number of different means. Once conditions appear to be declining, maintenance is scheduled in order to restore the machine to its previous level of reliability. 

Examples of what kind of elements are monitored in condition-based maintenance include: 

• Sound. If a machine that normally has a steady running sound exhibits changes in the noise it makes, condition-based maintenance may be needed. 

• Temperature. Faulty electrical wiring or other failed machine components may change the temperature of a piece of equipment, triggering preventive maintenance. 

• Vibration. Pumps, motors or compressors may vibrate differently than usual, indicating that they need lubrication or some other form of preventive maintenance. 

• Visual. Looking for surface cracks or other visible corrosion is one of the most simple forms of condition-based maintenance.

Types of Preventive Maintenance Tasks

Within each type of preventive maintenance, certain maintenance tasks can be further divided into categories based on their importance and priority. These specific tasks can be time-based, usage-based, condition-based, or a combination of the three. 

Types of preventive maintenance tasks include: 

• Mandatory Tasks. Mandatory tasks must be performed exactly as scheduled or as soon as they are due in order to avoid equipment failure. This can include emptying out a waste container or cooling a certain equipment component every night. 

• Non-Mandatory Tasks. Though still vitally important, non-mandatory maintenance tasks can be delayed or rescheduled without immediately risking critical equipment failure. Non-mandatory tasks may include surface inspections or certain kinds of component cleaning.

• Pyramiding Tasks. If a maintenance task is scheduled for a certain time but the due date is missed and the task overlaps with other scheduled maintenance, it may be considered a pyramiding task. In this situation, the performer of the new task should make note of the original missed maintenance and monitor how overdue the task is. 

• Inspection Tasks. Some maintenance tasks, especially condition-based ones, can only be undertaken once an inspection is performed. In this case, the inspection and the maintenance are separate, and the maintenance task should be scheduled only after an inspector has identified any problems. 

• Task-Oriented Tasks. Task-oriented preventive maintenance duties include situations in which maintenance can be performed at the same time as inspection. This can reduce the amount of time, money, and man-hours expended on any one maintenance task. 

What is a Preventive Maintenance Checklist? 

A preventive maintenance checklist is a list of tasks, targets, and/or procedures that should be performed as part of a larger maintenance plan.

Preventive maintenance checklists are typically created in collaboration with a maintenance manager, on-the-ground workers, inspection contractors, and regulatory bodies. Many industrial companies use preventive maintenance software to help create, track, and document their preventive maintenance checklist. 

Benefits of a Preventive Maintenance Checklist 

Like all aspects of preventive maintenance, preventive maintenance checklists aim to increase efficiency, decrease downtime, and make workers safer. 

Some other benefits of a well-made preventive maintenance checklist include: 

• Decreased human error 

• Improved diagnostics

• Faster inspections

• Specialized training 

• Streamlined maintenance planning

• Workplace continuity and consistency

Preventive Maintenance Checklist Examples

Preventive maintenance checklists will vary from industry to industry and company to company, but many are based on a similar premise and goal. 

Below are examples of a preventive maintenance checklist in three different industries. 

Building Interior Preventive Maintenance Checklist

• Examine for visible evidence of deterioration

• Check for leaks

• Inspect for electrical, slipping and tripping, and falling hazards

• Check the condition of the toilets and showers

• Test smoke and carbon monoxide detectors

• Test the fire alarm system

• Check fire extinguishers and any fire fighting equipment

• Check doors for proper operation and make sure that exits are not obstructed

• Inspect door locks and closures

• Ensure work areas and walkways are clearly and visibly marked

• Check for garbage in storage areas

• Check for evidence of insect or other pest infestation

• Inspect cart casters for signs of wear

• Make sure that shelving is secure, organized, and labeled

• Inspect electrical receptacle cover plates for tightness and damage

• Confirm that controls such as timers and photocells are functioning

Network and Data Systems Preventive Maintenance Checklist

• Review network security practices

• Regularly review and identify the immediate threats to network security 

• Assure that employees comply with safe practices such as password security and good email practices

• Change Wifi and other network passwords at least twice a year

Semi Truck Preventive Maintenance Checklist

• Perform standard safety check

• Lubricate necessary components

• Check brakes

• Check lights

• Check tire condition/inflation

• Top off fluids

• Check and adjust high-wear components

Drones in Preventive Maintenance

Preventive maintenance can be performed in a number of ways, but many start with visual condition monitoring.

One of the fastest and most technologically advanced ways to perform preventive maintenance tasks is with the use of drones or uncrewed aerial vehicles (UAVs).

Agile and nimble UAVs can be an incredible aid to all types of preventive maintenance. Drones can help monitor equipment status in the case of condition-based monitoring, and can help with or even autonomously perform certain time-based or usage-based preventive maintenance tasks.

At times, an asset will not have to be turned off in order for the drone to complete a visual inspection, meaning production continues. Other times, a drone will significantly reduce downtimes by eliminating the need to build scaffolding to complete a visual inspection.

In this Flyability case study, the Elios 3—equipped with a LiDAR sensor—is used for the City of Lausanne's Water Department inspections in order to plan, track, and implement maintenance schedules. The LiDAR maps created in real time keep track of the assets over time, providing accurate reports of wear and tear.

Drones cut down on the cost and time that needed to perform certain preventive maintenance tasks, but also that UAVs keep inspectors out of dangerous and confined spaces.

With no reason to put themselves in the radius of machinery that could potentially be malfunctioning, workers are able to remain safer by using Flyability’s Elios drones.

An Elios 3 drone performing a visual inspection