September 2019

Maintenance and Reliability

Are there ghosts in your maintenance backlog?

The heart and soul of a maintenance organization is often found in the backlog of identified work.

Thorman, G., Red Horse Properties LLC

The heart and soul of a maintenance organization is often found in the backlog of identified work. However, this work is not only the ready work. The complete backlog includes all work approved by operations, as well as the ready-to-schedule (RTS) work, which is work that is approved, planned and ready to schedule. Sometimes, maintenance managers report only a portion of the backlog and have no idea what work might be “in planning” without a labor estimate assigned. This “ghost” part of the backlog is not the ready work, but rather the rest of work.

For practical purposes, such as tracking, the ghost portion of the backlog does not exist except as a count in the raw number of jobs. Since no labor estimate is associated with the ghost work, none is reportable in the official backlog reports. Complete, well-managed and understood backlog data can answer many questions and are contributors to key performance indicators (KPI). Questions that can be addressed with complete backlog data include:

  • Is the plant maintenance workforce the right size, and does it possess the necessary craft skills?
  • Are contractors being used as a component or a crutch?
  • Has overtime become a necessary evil or a valuable tool?
  • Does the backlog contain preventive maintenance (PM) work or major annual shutdown work?
  • Is training, shop cleaning, etc., an annual large allotment placed in the backlog?
  • Does the backlog contain standing or blanket work orders?
  • How long do jobs spend in the backlog? Do jobs linger in the backlog for more than 6 mos or 1 yr?
  • Is the status and movement of backlog jobs transitioning through the computerized maintenance management system (CMMS) known?
  • Is a backlog review and cleansing process in place?
  • What is the size of the complete backlog? By craft skill?

It is beneficial to examine the entire picture of what constitutes good backlog management using solid data. Achieving best practice numbers should be based on the backlog database, and ghost jobs should be revealed.

Qualifying for the maintenance backlog report

Most plants have a clear path for job maintenance requests, usually via a CMMS work order system. Efficient plants use an approval step before customer requests proceed to maintenance. The approval step is a clear portal and exists to cull out duplicate requests, unnecessary work or expensive work not provided for in the budget. Up to the portal, the request is considered a work order request that has yet to be confirmed and approved by the purse strings of operations. This work does not become part of the backlog until such approval has been given. At the point of approval, the work request transitions from a request status to a bona fide work order with a work order number assigned by the CMMS. Only then does it enter the CMMS “in-planning” status of the maintenance department and the maintenance planner.

Ghost backlog

Too often, approved jobs linger in the CMMS status of in planning without any planner action and without any labor estimate—here lies the hidden ghost backlog. The job, for all backlog size calculations, does not exist in the backlog calculation of labor weeks until the planner assigns a labor estimate. Plants too often skip over these jobs and focus solely on the RTS backlog when doing backlog size calculations. Ghost backlog jobs may be large, yet for most measurements can only be captured as a job with unknown size and craft skill required. Tracking total backlogs by a simple number count reveals very little other than if the number of jobs is increasing or decreasing over time.

A ghost job of 500 hr of labor counts the same as a job requiring 2 hr. Further misleading conclusions can occur when sister plants compare their job counts to each other rather than using actual hours. Without exception, larger plants have more work orders. This reveals nothing beyond what common sense dictates. Tracking the number of work orders means very little.

The solution to ghost backlog jobs is straightforward. All new work, once approved, is immediately given a rough estimated labor number in hours. Planners are instructed to enter this number into the CMMS as soon as possible. It is not meant to be a well-planned estimate but rather a rough estimate, and it can be easily changed after planner investigation and before becoming an RTS job. For compliance purposes, planners are subject to a metric revealing what percent of their backlog has a number in the labor estimate field, by craft. The target is 90%. From experience, planners readily understand this need and can quickly bring their estimated backlog numbers up to the 90% goal. The tracking metric in TABLE 1 identifies the planners that are struggling with this responsibility.

FIG. 1. The age of CMMS jobs within the complete backlog.
FIG. 1. The age of CMMS jobs within the complete backlog.

Calculating a backlog

It is recommended to track the backlog as both the complete backlog and the RTS backlog (which are planned jobs, with needed parts onsite and ready to be potentially placed on the schedule). The complete backlog measures how much work in labor-weeks exists for maintenance, while the RTS backlog indicates the amount of work that can be selected for the next week’s schedule. Both are valuable, but the complete backlog is required for many metric questions and should be used to discern how big the backlog is and if remedial actions to lower (or increase) it are needed. Complete backlogs quickly indicate many keys to maintenance management decisions. Ghost portions of backlogs do not. FIG. 1 is from a major oil producer and reveals the age of CMMS jobs within the complete backlog. The goal was to reduce aging jobs of more than 30 d.

Backlog calculation

The backlog calculation is simple and should answer the following question: “How many weeks, based on crew size, would it take a specific maintenance work crew to complete all known routine work in the backlog?” The answer is usually given in crew-weeks (or labor-weeks), but the calculation must allow for several variables. A solution that can be used includes:

  1. How large is the crew by craft designation and by area, if assigned per week? This is the gross
    amount of time available to work on jobs each week (generally, 40 hr multiplied by the crew head count).
  2. The following must be discounted:
    • Average hr/week (over 1 yr) crew members have for vacation, holidays and training. Blanket/standing work order hours may also be included.
    • Average hr/week (over 1 yr) crew members spend on PMs or PdMs.
    • Average hr/week (over 1 yr) crew members spend on emergency work (based on the percent of emergency work).
    • Weeks are based on 52/yr. If major annual shutdown(s) occur, these shutdown weeks would be discounted from the 52.
  3. The discounts then become the net amount of labor time in hours, available for the routine backlog work each week.
  4. Next, the size of the complete backlog must be determined in estimated hours.
  5. The total hours of the complete or RTS backlog must be divided by the net amount of labor time available.
  6. The result is the number and size of the complete or RTS backlog in crew-weeks.

Complete backlog report details

Crew-weeks are needed for each craft skill, in each area department. When multiple, designated and different crafts (millwrights, pipefitters, welders, etc.) exist across multiple area assignments, each crew has its own backlog, just as if there were only two centralized electrical/instrument and mechanical designated crews. Each specific skill contains a backlog because each crew is a specific work group. Reporting backlogs by the entire maintenance department gives little indication of which areas have high or low backlogs. This way of reporting may work for corporate summary reports, but it does little to clarify the details of a plant’s separate maintenance crew backlog number.

Embedded contractors should also be included in the crew size when they are used daily. It is unnecessary to include contractors used on an infrequent basis in complete or RTS backlog reports. As with overtime, the use of contractors can provide a solution when trying to reduce high backlogs. Consistent high backlog numbers may necessitate an increase in crew size. Conversely, low backlog numbers (less than 2 wk) should prompt a decision to reduce contractors, overtime or crew size. Of course, before any changes are made, a backlog review should be performed to identify backlog “junk.” Junk includes work orders that are more than 1 yr old, duplicate work orders and work orders that have been completed or are near completion and not yet closed. To identify work that has been completed but not closed, columns should be added to the backlog report that show by job, labor hours and materials used to date. Numbers in either or both columns suggest that a job is finished/close to finished and has not been closed. Note: A job with 500 estimated hours and only a few hours yet to be completed will typically count as 500 hr in a backlog report. Until a job is completed/closed, the entire amount is counted by the CMMS report.

For KPI goals, consider 3 wk–4 wk of complete backlog and 2 wk–3 wk of RTS backlog numbers.

What is not in a routine backlog?

Many jobs can slip into a backlog that do not belong, thereby incorrectly increasing the backlog size. The most prominent increase often includes jobs targeted for an annual shutdown. These jobs will greatly inflate the backlog until the shutdown is complete. Annual shutdown jobs should have their own backlog classification. PM jobs are another backlog inflator. Since PM work is discounted from a backlog calculation, PMs should not be in the routine backlog calculation. Again, such bulk high-hour additions for the entire year tend to inflate the backlog size until after the entire year is completed and should not be included. In the same category are blocks of time placed in the routine backlog for annual training, blanket/standing work orders or other grouped hour categories. Annualizing and then factoring in a weekly average to discount from the gross time available is the preferred method to ensure that a backlog is not distorted.

Backlog management process metrics

The following metrics travel with and are part of a good backlog analysis:

  • Crew-weeks of backlog, by area and skill.
  • Craft overtime by area and skill.
  • Maintenance contractor hours or head counts.
  • Percent of backlog in each major CMMS status (approved, in planning, waiting on parts, RTS, scheduled, completed and closed). These numbers
    can point to bottlenecks in the process.
    TABLE 2 shows the tracking of complete backlog jobs in RTS status. The goal for RTS at this plant was 70%.


Backlog management is a key component of maintenance management. Backlogged jobs are a measurement of risk, as delays in repairs can result in higher degrees of growing failure cost outcomes. Plants that monitor and carefully track their backlogs with clear information will continually make better decisions for increased plant reliability and reduced costs.

The following 10 points are the basis for good backlog management:

  1. Use both a complete and RTS routine backlog metric.
  2. Require planners to enter rough labor estimates into a new job as soon as possible.
  3. Use a disciplined formula for determining the backlogs in craft-weeks of work.
  4. Track backlogs by both craft skill and area.
  5. Clean up the existing backlog (old, obsolete, duplicate, near-finished jobs).
  6. Do not include jobs associated with annual shutdowns in the routine maintenance backlog. Use a separate backlog.
  7. Do not insert large numbers (such as the entire year of training or PM hours) into the backlog. Rather, average these jobs over 52 wk and discount them from the gross hours available each week.
  8. Track the percentage of work in each of the major CMMS status categories, from in-planning through complete, to see how quickly work progresses.
  9. Follow the metrics for overtime and contractor hours to see if these are increasing while the backlog decreases.
  10. Strive for 2 wk–3 wk of RTS backlog and 3 wk–4 wk of complete backlog. HP

The Author

Related Articles

From the Archive



{{ error }}
{{ comment.comment.Name }} • {{ comment.timeAgo }}
{{ comment.comment.Text }}