Corrective maintenance (CM) refers to unscheduled actions taken to restore equipment to operational condition after failures are discovered. It includes five types: fail-repair, salvage, rebuild, overhaul, and servicing, each addressing different aspects of equipment restoration. The corrective maintenance process involves five sequential steps: fault recognition, localization, diagnosis, repair, and checkout, with various components contributing to downtime.

1. Corrective Maintenance (CM)
R. M. SHAHBAB
Lecturer, Department of IPE, BUET
Email: sshahbab@ipe.buet.ac.bd

2. Reference
Chapter 5 - Engineering Maintenance, A Modern
Approach,
B.S. Dhillon, CRC Press, 2002

3. Thread Standards and Definitions
Introduction
 Corrective maintenance may be defined as the remedial action carried out
due to failure or deficiencies discovered during preventive maintenance,
to repair an equipment/item to its operational state.
 Corrective maintenance is an unscheduled maintenance action, composed
of unpredictable maintenance needs.

4. Thread Standards and Definitions
Corrective Maintenance Types
There are five type of corrective maintenance:

5. Thread Standards and Definitions
Corrective Maintenance Types
 Fail-repair: The failed item is restored to its operational state.
 Salvage: This element of corrective maintenance is concerned with
disposal of nonrepairable material and use of salvaged material from
nonrepairable equipment/item in the repair, overhaul, or rebuild
programs.
 Rebuild: This is concerned with restoring an item to a standard as close
as possible to original state in performance, life expectancy, and
appearance. This is achieved through complete disassembly, examination
of all components, repair and replacement of worn/unserviceable parts as
per original specifications and manufacturing tolerances, and reassembly
and testing to original production guidelines

6. Thread Standards and Definitions
Corrective Maintenance Types
 Overhaul: Restoring an item to its total serviceable state as per
maintenance serviceability standards, using the “inspect and repair only
as appropriate” approach.
 Servicing: Servicing may be needed because of the corrective
maintenance action, for example, engine repair can lead to crankcase
refill, welding on, etc. Another example could be that the replacement of
an air bottle may require system recharging.

7. Thread Standards and Definitions
Corrective Maintenance Steps
We assume that corrective
maintenance is composed of five
major sequential steps: fault
recognition, localization, diagnosis,
repair, and checkout

8. Thread Standards and Definitions
CM Downtime Components
Major downtime components are:
 Active repair time:
 Preparation time
 Fault location time
 Spare item obtainment time
 Fault correction time
 Adjustment and calibration time
 Checkout time
 Administrative and logistic time
 Delay time