Corrective Maintenance

In asset management and equipment maintenance, corrective maintenance is key. While preventive maintenance is about avoiding failures through regular inspections and servicing, corrective and breakdown maintenance come into play when issues arise. Corrective maintenance is fixing equipment when issues are identified, breakdown maintenance is fixing equipment that has already failed. Understanding corrective maintenance is important because it can lead to big cost savings and efficiency gains by finding problems before they escalate—especially when supported by a corrective maintenance workflow.

Corrective Maintenance Definition

Corrective maintenance is a set of actions to get equipment or an asset back to working order after a failure, malfunction or performance drop below acceptable level. In other words, corrective maintenance is fixing problems that have already occurred, not preventing them.

Unlike preventive maintenance which is done according to a schedule before problems arise, corrective maintenance is a reactive approach. This is the whole philosophy of the approach: we react to events rather than try to prevent them. Many times maintenance tasks are tracked and scheduled in a CMMS to prevent repeated failures.

It’s important to understand that corrective maintenance is part of the broader concept of reactive maintenance. Reactive maintenance is the umbrella term for all types of maintenance performed in response to an event that has already occurred. This helps to clearly distinguish the corrective approach from the preventive one, where preventive maintenance tasks are planned in advance, regardless of the current state of the equipment.

Types of Corrective Maintenance

Many people think all corrective maintenance is chaotic emergency repairs. In fact there is a big difference:

1. Unplanned Corrective Maintenance

This is the classic emergency repair scenario: equipment fails, production stops and the maintenance teams scramble to fix the problem. This type of maintenance is often referred to as emergency maintenance—it has the highest priority and needs to be done immediately, especially when there is a risk to personnel safety or critical production line downtime. Unplanned corrective maintenance is critical to keep production running and prevent unexpected breakdowns.

2. Planned Corrective Maintenance

Planned corrective maintenance is when a problem is detected (e.g. through condition monitoring) but the repair is deferred until a more convenient time. Imagine vibration sensors are showing increased bearing wear but the condition is still not critical. Instead of immediate repair you schedule the replacement for the next weekend when production is down.This is the difference between breakdown vs. unplanned. Deferred repair (immediate vs deferred repair) is key to proper work prioritization and risk management. Proper scheduling helps reduce corrective maintenance costs and optimize maintenance tasks.

3. Predictive Corrective Maintenance

This type of maintenance is when an issue is found through monitoring or diagnostics before it leads to a full breakdown. The goal is to fix the problem at the right time—before it causes major damage. Techniques like condition monitoring help detect early signs of failure.

4. Reactive Corrective Maintenance

Reactive CM includes both emergency (unplanned) and deferred (planned) repairs—anything performed after a failure has been detected. This is the most basic form of corrective maintenance—fixing things only when they break. While it’s unavoidable in some cases, relying too much on reactive maintenance can lead to higher costs and longer downtimes. The difference between the 1st and the 4th type is that immediate corrective maintenance focuses on urgent, high-priority repairs, while reactive maintenance covers all post-failure fixes, whether urgent or not.

Advantages of Corrective Maintenance

Maintenance tasks are essential to get equipment back to working order and minimize the impact of failures. Equipment failure can impact production, safety and costs, so you need to address these failures quickly by performing corrective maintenance processes. Here are the benefits:

• Restores Production. Equipment failure means production delays, missed deadlines and lost revenue. Immediate corrective maintenance helps you get back up and running as quickly as possible to minimize downtime and maintain productivity. Tracking and measuring maintenance tasks is key to evaluate effectiveness and guide decision making on maintenance strategy.
  
• Cost Effective for Non-Critical Assets. While a preventive maintenance program is important for critical equipment, corrective maintenance can be more cost effective for non-essential equipment that don’t need frequent servicing. By focusing on what’s needed, maintenance teams can reduce unnecessary maintenance tasks and costs.
  
• Improves Workplace Safety. Addressing failures immediately prevents accidents and ensures compliance with safety regulations. Corrective maintenance keeps the workplace safe by fixing issues that can harm employees. Even simple unscheduled corrective maintenance tasks, like repairing a broken guard or faulty sensor, can prevent accidents.
  
• Balanced Resource Utilization. A balanced approach that combines routine maintenance, corrective maintenance work and predictive methods allows you to optimize maintenance tasks and resource allocation. Critical assets get the attention they need while non-essential equipment is maintained cost effectively. This reduces corrective maintenance frequency over time

Corrective Maintenance Process

Corrective maintenance can’t happen without a process. Modern organizations use a corrective maintenance workflow: a work request → work order flow — from the moment a defect is detected to its complete resolution.

Process steps:

Stage	Definition
1. Problem detection	An operator, monitoring system or scheduled inspection finds a fault or deviation from the norm. Early detection helps to reduce corrective maintenance by avoiding total equipment failure.
2. Work request creation	A corrective maintenance request is created in the CMMS (Computerized Maintenance Management System) with a description of the problem, the asset location and a preliminary criticality assessment. This allows maintenance teams to track and prioritize issues.
3. Evaluation and prioritization	The foreman or scheduler evaluates the request using a priority matrix (criticality × impact):Asset criticality for productionConsequences of failure for safety and businessUrgency of problem resolution.
4. Work order creation	An approved request is converted into a corrective maintenance work order with specific maintenance tasks, assigned performers and necessary tools and spare parts. This ensures maintenance technicians know exactly what to do.
5. Spare Parts Kitting	Having all necessary components ready before work begins is crucial. Having essential parts ready minimizes downtime during corrective maintenance.
6. Work Execution	Technicians perform repairs, following safety procedures (LOTO) and documenting all actions in the CMMS. Clear maintenance tasks improve efficiency and reduce the chance of repeated failures.
7. Post-Repair Verification & Run Test	After repairs are completed, a functional check and load test are required to ensure there are no residual defects and full functionality has been restored. This step reduces the likelihood of unexpected breakdowns.
8. Work Order Closure and Analysis	The work order is closed with the actual time, materials used and a description of the work performed. This data helps to reduce corrective maintenance over time by analyzing patterns and improving the maintenance strategy.

MTTR, MTBF and the Impact of Corrective Maintenance

Two maintenance performance indicators (KPIs) are directly related to corrective maintenance:

MTTR (Mean Time to Repair)

This is the average time to repair and get the equipment back in service. Corrective maintenance needs to be fast and efficient to lower MTTR. The faster repairs are done the less downtime and total equipment failure occurs.

Ways to reduce MTTR:

• Pre-assembling essential parts (kitting)
• Clear standard operating procedures
• Trained personnel
• Efficient dispatching system
• First-time fix

MTBF (Mean Time Between Failures)

This measures equipment reliability. Good corrective maintenance with root cause analysis (RCA) can increase MTBF by fixing not just the symptoms but the root causes of failures.

Root Cause Analysis: Transforming Reactive into Proactive

The biggest mistake in corrective maintenance is to only fix the symptom and not the root cause. A root cause analysis (RCA) after each significant corrective maintenance will allow you to:

• Find the true cause of a failure (not the trigger).
• Prevent similar problems from happening again.
• Reduce unplanned maintenance in the future.
• Identify assets for preventive or predictive maintenance.

RCA Methods:

• 5 Whys: A simple technique where you ask the question “Why?” five times, working your way from the symptom to the root cause.
• Fishbone Diagram: A visual tool to systematically analyze all possible causes of a problem by category: people, methods, machines, materials, measurements, and environment.
• Failure Mode and Effects Analysis (FMEA): A systematic method to analyze potential failures and their consequences. FMEA linkage with corrective maintenance helps to determine where CM is acceptable and where PM or CBM (condition-based maintenance) must be implemented.

Failure Modes & Effects: when CM is Acceptable and when not

In FMEA, each failure mode is assigned a Risk Priority Number (RPN)—a risk priority number calculated as the product of three factors:

• Severity (consequences of failure)
• Occurrence (probability of occurrence)
• Detection (probability of detection using monitoring tools).

Rule for using CM based on RPN:

RPN	Maintenance strategy	Explanation
1–50	Run-to-failure maintenance allowed	Low risk, CM is cost effective for equipment health
51–120	Planned CM + periodic maintenance inspections	Medium risk, needs regular checks
121–250	Preventive maintenance required (preventive tasks)	High risk, preventive work is needed
251+	CBM/PdM + backup	High risk, maximum protection required

Run-to-failure maintenance is acceptable for non-critical equipment where failures have minimal impact on operations.

Priority Matrix: What to Fix First?

The priority matrix (criticality × impact) helps decide what to fix first, assigning tasks from P1 (emergency) to P5 (low).

Priority matrix:

Impact on production	High impact	Medium impact	Low impact
Critical	P1 (immediately)	P2 (within 1 hour)	P2 (within the shift)
Important	P2 (within 1 hour)	P3 (within the shift)	P4 (within the day)
Minor	P3 (within the shift)	P4 (within the day)	P5 (when possible)

• P1 — Emergency: Safety risk or total shutdown of a critical line; emergency maintenance window activated with separate SLAs (Service Level Agreements).
• P2 — Urgent: High impact on production, requires quick response.
• P3 — High: Repair during the current shift.
• P4 — Medium: Can be scheduled for a convenient time during the day.
• P5 — Low: When possible.

Using this matrix ensures essential equipment is running at optimal performance and aligns with reactive maintenance for non-critical ones.

Examples of Corrective Maintenance

Let’s see specific examples of corrective maintenance from real-life production practices:

Example 1: Replacing a Burnt-Out Light Bulb

The simplest corrective maintenance example is replacing a burned-out light bulb in a shop floor. The lamp has stopped working (the failure has been detected), and an electrician receives a request through the CMMS and replaces it with a new one. This is typical unscheduled, low-priority corrective maintenance.

Example 2: Repairing a Leak in a Hydraulic System

An operator discovers an oil stain under a hydraulic press. The leak is not critical, but requires repair. The foreman inspects the system, identifies a worn seal, orders a replacement component through the replacement components availability (kitting) system, and schedules the replacement for the next day during breaks. This is an example of planned corrective maintenance.

Example 3: Emergency Conveyor Repair

During operation, a conveyor belt on the main production line breaks. Production is stopped. This is emergency maintenance with the highest priority according to the priority matrix (criticality × consequences). The team immediately implements safety lockout/tagout (LOTO) procedures, secures the equipment and initiates emergency repairs. A downtime cost model shows that every minute of downtime costs thousands of dollars.

Example 4: Motor Replacement after Vibration Analysis

The condition monitoring system detects abnormal vibration in the electric motor. An engineer conducts an in-depth analysis and determines that the bearings are 70% worn. A critical failure is predicted within 2-3 weeks. Replacement components are ordered and a maintenance shutdown is planned. Here, it is used to schedule planned corrective maintenance.

Corrective vs. Preventive vs. Predictive: Choosing a Strategy

Understanding the differences between maintenance strategies is critical to optimizing costs and reliability.

Characteristic	Corrective (CM)	Preventive (PM)	Predictive (PdM)
When it is done	After a failure	On a schedule	Based on equipment condition
Implementation cost	Low	Medium	High
Operating costs	High (downtime)	Medium	Low
Required technologies	Basic CMMS	CMMS + planning tools	CMMS + IoT + analytics
Downtime	Unplanned, long	Planned, short	Minimal, planned
Suitable for	Non-critical assets	Essential equipment with predictable wear	Essential equipment with monitoring available

The average maintenance cost structure for a production facility is:

• 30% — Preventive Maintenance
• 45% — Predictive Maintenance (monitoring and forecasting)
• 20% — Planned Corrective Maintenance
• 5% — Emergency Corrective Maintenance

If emergency CM is more than 15%, there’s a problem with the strategy.

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