Failure-based Maintenance (FBM) is unscheduled maintenance or repair to return the asset to a defined state. There are no interventions until a failure has occurred.

This includes the Reactive Maintenance and the Run to Failure (RTF) Maintenance.

Many are not differentiating between the above-mentioned types of Maintenance and use the two terms as alternatives.

So, I developed this diagram to show the difference between them, also to show the relation between them and the CM.

Figure-1: The Relation between Reactive, Run to Failure (RTF), and Corrective Maintenance (CM)

Reactive Maintenance (unplanned) is the oldest type of maintenance.  It is the required repair, replacement, or restore action performed on an asset or a facility after the occurrence of an unexpected failure to bring this asset or facility to at least its minimum acceptable condition.

It is subdivided into two types:

1. Emergency Maintenance (urgent):
   It is carried out as fast as possible to bring a failed asset or facility to a safe and operationally efficient condition. Emergency Maintenance is 3 to 5 times as expensive as ‘normal’ preventive maintenance.
2. Breakdown Maintenance (not urgent):
   It is performed after the occurrence of an advanced considered failure for which advanced provision has been made in the form of repair method, spares, materials, labor, and equipment

In both above cases, an item of plant or asset is completely unable to function.

Both Reactive Maintenance and RTF Maintenance are carried out after the failure occurrence, but RTF is not a reactive maintenance, as Mr. Ramesh Gulati stated in his book “Maintenance and Reliability Best Practices”:
“RTF is a maintenance strategy where the organization decides to allow specific assets/systems to fail without any PM or CBM performed against them. This strategy is NOT the same as reactive maintenance (In reactive maintenance, an organization does not have a structured maintenance program, which would include elements of PM, CBM, and RTF spread throughout the facility, with each asset/system having its own specific maintenance strategy.)  For assets where the cost and impact of failure is less than the cost of preventive (PM and CBM) actions, RTF may be an appropriate maintenance strategy. It is a deliberate decision based on economical effectiveness.”

RTF is a consideration if the following main factors are satisfied:

1. Failure has zero HSE impact
2. Failure has minimum capacity (production) impact
3. Failure has minimum disturbance impact
4. Failure has minimum cost impact
5. Preventive or predictive maintenance are not cost effective
6. Assets are Non-critical

When the above mentioned failures occur, they need to be repaired through the CM. Figure-1 shows which types of repair will be considered unplanned and which will be considered planned.
Of course, CM also has input from PM and PdM programs, but these are caught before failure happens and in many cases can be corrected while the asset is still in service.