U.S. Army preventive maintenance activities over short and long term

Army preventive maintenance activities

Preventive maintenance activities must face frequent economic reviews to judge their efficiency. Maintenance managers can use their cost and technical data with this assessment to decide the cost-effectiveness of their preventive maintenance activities.

Preventive maintenance activities often only show returns in the long term.  Therefore, it is critical to run regular economic reviews of preventative maintenance activates, to chart their efficiency and effectiveness. Though cost and technical data will differ between maintenance managers and their assets, general ideologies for managing systems remain. The U.S. Army follows a strict set of guidelines for their preventive maintenance activities, examined in detail here.

preventive maintenance activities
Correlation of PM level and elapsed time (years) before unit failure.

Preventive maintenance activities of a unit are handled based on priorities, human and financial resource availability, and the unit’s technical data and it’s preventive maintenance program. Maintenance managers should take note that different reasons exist for keeping a PM activity on their work roster and for scheduling a PM activity. The decision of whether or not to add an activity to the PM work roster is based on the value of an activity to the installation, as well as the activity’s cost-effectiveness. Whether or not to schedule a PM activity relates to the coordination and timeliness of the activity.

To effectively schedule preventive maintenance activities, managers must have knowledge of priorities and available resources. Depending on how often operations systems require inspections and servicing, PM scheduling can be fixed (required and performed at set times), variable (required, but with flexibility), or optional (preferable, but can be skipped without consequences).

Maintenance managers should take care to collect and interpret maintenance data regularly, building complete maintenance histories from their operations records (using preventive maintenance software can help).

The history of a unit should include the unit’s installation date, repair, maintenance, and inspection records of the unit, and the unit’s type and cost of replaced parts. This allows for managers to enter accurate and regular proposed maintenance schedules.

Using the maintenance data collected over time, including fail-rates, managers can determine the benefits of a preventive maintenance program. This can be calculate by the net savings gained by performing PM on a unit, over not performing PM. Managers can use this information to define trends, which can be charted out into graphs for easier understanding. The information generated by maintenance data and their charts can extend the overall life of a unit.


References | The Value Assessment Method for Evaluating
Preventive Maintenance Activities

 

The difference between predictive and preventive maintenance programs

propellars preventive maintenance

A predictive and preventive maintenance program is essential to efficient, reliable and safe operations. However, it takes tons of discipline.

Predictive and preventive maintenance programs (PPM) involves the regular and systematic application of engineering knowledge and maintenance of equipment and facilities. PPM ensures proper functionality and reduced rates of deterioration of facilities and equipment.

To work effectively, predictive and preventive maintenance programs involve dedicated engineering, regular examinations, inspections, lubrication, testing and adjustments of equipment without prior knowledge of equipment failure. Combined, these tactics work to prevent equipment failure, and should not be reserved only for equipment that has presented problems in the past.

preventive maintenance program experiment
PM doesn’t achieve reliability, it preserves reliability!

PPM also involves creating a framework for all planned maintenance activity, including planning work orders to correct potential problems identified by inspections. The desired effect of a properly implemented PPM program is a proactive, rather than reactive, workplace environment.

Total maintenance cost of equipment owned is the sum total of the material cost, as well as the labor cost to repair the item, the preventative maintenance costs to avoid repairs, and the cost of lost production while the item is being repaired. Predictive and preventive maintenance is designed to extend the life of equipment, and reduce unnecessary failures and repairs by implementing a selective program effort for corrective, or “fix it when it fails” maintenance.

Requirements of predictive and preventive maintenance programs

Predictive maintenance monitors the condition and performance of equipment to detect units’ degradation. To do this, predictive maintenance utilizes testing and measuring techniques to determine the status of equipment before breakdowns occur. These predictive maintenance programs complement preventative maintenance, however to be successful a few things must happen. After predictive maintenance is performed, it is used to determine preventive maintenance, which is a performed at regular intervals on a piece of equipment to lessen its likelihood of failure. For example, predictive maintenance can determine that a unit must be checked every two weeks to avoid failure. Preventive maintenance would then be performed at those intervals.

Diligent scheduling creates success in preventive maintenance, while predictive maintenance contributes to diligent scheduling. Predictive and preventive maintenance must stick to a planning and schedule program, providing structure into which PPM routines follow. If they are not followed, the environment will remain reactive. The greatest barrier to effective scheduling is the occurrence of emergency breakdown repairs, which can distract a maintenance crew from their other duties. However, if a crew follows a predictive and preventative maintenance program diligently, these emergency breakdown repairs all but be eliminated or reduced to a minimum.

Predictive and preventive maintenance programs must be viewed as an ongoing and controlled experiment to maintain consistency and punctuality. Just as one continually nurtures and refines an experiment, controlling for variables and sticking to schedules, maintenance engineers must do the same for PPM or the program will fall apart. An effective maintenance engineer will design a personalized PPM program and schedule suited to their company’s industry, assets, and equipment. Studies have found the preventive maintenance ROI is  $0.33/ square foot.

 


References | Life Cycle Engineering Preventive and Predictive Maintenance

 

JLL calculates preventive maintenance ROI

preventive maintenance roi

At a 545% ROI and with cost reductions totaling $0.33 a square foot, preventive maintenance savings are worth the investment.

Preventive Maintenance (PM) is vital for the effective functioning of all equipment across many industries.

While preventative maintenance has been a priority for most companies, there is less clarity on what kind of value it has with regard to returns. A better approach is to streamline a process for assessing how preventive maintenance software provides value through the lens of financial ratios. The lack of concrete statistics and evidence-based examinations point to the need for evaluating preventive maintenance with reference to mitigating risks and protecting assets.

A perfect example of quantifying the preventive maintenance ROI can be seen in an analysis carried out by a company to create a financial model, in partnership with Jones Lang LaSalle (JLL). The analysis explored the current value and investment returns gained upon funding preventive maintenance for portfolio of buildings.

preventive maintenance ROI JLL
1. NPV of preventive maintenance is calculated by comparing repair, energy and replacement costs for PM and non-PM scenarios and bringing the costs to a present value using an assumed discount rate. 2. EUL refers to estimated useful life.

Criteria used for assessing the utility of preventive maintenance included the equipment’s actual costs, costs involving repairs, costs involving replacements, the expected life cycle and effects of preventive maintenance on life cycle. It also comprised of the frequency of repairs required when the equipment is in poor condition and the consequences of preventive maintenance on energy usage.

To start out, 12% of the company’s portfolio was surveyed – approximately 14 million square feet. For every property, the type of equipment, the number of equipment, size and age of equipment as well as expenditures incurred for preventive maintenance was calculated.

The financial model was compiled using the following assumptions: discount rate of 10%, inflation rate of 3%, time horizon of 25 years, non-productive lead time of 10% and lost revenue due to downtime at zero (i.e. this could not be quantified due to downtime). Based on this model, the team could pinpoint the effectiveness of preventative maintenance on specific equipment.

For example, if a company has an air compressor of 7 horsepower that is 10 years old, will it make sense to invest in replacing the compressor at $32,900 or utilize preventive maintenance? According to the model, the compressor would last 20 years with preventive maintenance versus 16 years without it. The preventive maintenance costs would amount to only $472 per year.

In addition, the team explored three possible scenarios related to preventative maintenance programs. The first one assumed that a company is having zero spending on preventive maintenance. The second one assumes that the cost of preventive maintenance is the actual amount spent at the time of analysis. The third scenario assumes that the company spends what is known as the industry benchmark on preventative maintenance measures. The results when comparing scenario 1 to 3 showed that preventative maintenance brings huge returns in investment. Returns are chiefly due to maximising on the full life potential of equipment.

 


References: Determining the Economic Value of
Preventive Maintenance, a study by JLL

 

Corrective vs Preventive Maintenance Savings: Railway Infrastructure Case Study

preventive maintenance savings train

Rail infrastructure is used to examine the relationship between corrective and preventive maintenance. 70–90% of costs are tied to corrective maintenance.

To show the relationship between preventive maintenance costs and corrective maintenance costs, a study was run examining railway infrastructure maintenance in the US. In the case study, the 10 most expensive railway sections were found to have four times higher maintenance cost than the 10 least expensive railway sections. This is attributed to the fact that the costliest sections transported three times the tonnage compared to the sections with the lowest costs. For this reason, the costliest sections also experienced 4.5 times more track failures.

Corrective Maintenance Savings

Delving deeper into the maintenance costs reported, it was determined 70– 90% of the maintenance cost comes from corrective maintenance, which constitutes 61% of downtime (DT) and delay costs (see more on the 6:1 Golden Rule of Preventive Maintenance). Consequently, the results depend on the cost of DT. However, if the DT cost is disregarded in the case study, corrective maintenance still stands for 50 –70% of the maintenance cost of the railways. Corrective maintenance will always be necessary in an industry like railroads, where some variables are unpredictable, such as weather patterns that could rust railroad tracks or send trees falling. However, preventive maintenance can help ease the burden in cases where variables can be controlled.

preventive maintenance savings
Comparison of the 10 sections with the lowest cost with the 10 sections bearing the highest costs.

Preventive Maintenance Savings

While the costliest sections have the highest share of corrective maintenance, it was also found that the railway sections with the lowest total maintenance cost have the largest share of preventive maintenance: 30% preventive maintenance costs in the least costly sections – compared to 10% preventive maintenance costs for the costliest sections. This could be related to the difference in extent of the inspection frequency and quality. However, it was also found the railway sections with the lowest cost have lower preventive and corrective maintenance costs, which would be due to the fact that the highest cost sections were transporting three times more tonnage.  This is an example of why insiders must run effective cost-benefit analyses to decide which is best for their company regarding their industry and variables.

Preventive maintenance and corrective maintenance are both necessary for railway infrastructure to run successfully, however the costliest and least costly sections should be analysed differently due to the fact they transport extremely different amounts of tonnage. This fact holds true in any industry where operations might differ from each other.  An effective cost-benefit analysis can help companies decide which maintenance system might be most efficient for them, when applying the tips and rules mentioned in our summar of the cost benefit analysis of preventive maintenance.


References: Christer Stenström, Per Norrbin, Aditya Parida & Uday Kumar (2016) Preventive and corrective maintenance – cost comparison and cost–benefit analysis, Structure and Infrastructure Engineering, 12:5, 603-617, DOI: 10.1080/15732479.2015.1032983