Condition-Based Maintenance (CBM) is a maintenance approach in which the condition and performance of an aircraft system, engine or component are monitored to determine when maintenance attention may be required.
Rather than relying only on fixed calendar, flight-hour or flight-cycle intervals, condition-based maintenance uses operational and technical information to identify deterioration, abnormal behaviour or changes in performance that deserve engineering review.
The objective is to perform maintenance when the condition of the asset indicates that intervention is appropriate, while avoiding unnecessary work on equipment that continues to perform within expected limits.
How does Condition-Based Maintenance work?
Condition-based maintenance depends on monitoring relevant indicators over time.
Depending on the aircraft system or component, these indicators may include parameters such as temperature, vibration, oil consumption, pressure, performance trends, defect history or component behaviour.
Engineering teams review these signals against expected operating ranges, historical performance and the maintenance history of the asset. When a parameter begins to drift or exceeds an agreed limit, the finding can trigger further investigation, inspection or maintenance planning.
The monitored signal provides evidence for the review. The decision about what action to take remains with Engineering and Maintenance.
Condition-Based Maintenance in Aviation
In aviation, CBM operates within the wider approved maintenance and continuing-airworthiness framework.
Condition monitoring can help engineers understand how an aircraft system or component is performing between scheduled maintenance events, but it does not automatically replace mandatory maintenance tasks, Airworthiness Directives or other approved maintenance requirements.
Its value is particularly strong where teams can connect condition information with the aircraft's operational and maintenance history.
For example, an engine trend becomes more meaningful when Engineering can also see recent removals, shop visits, maintenance findings and installation history.
EXSYN's Engine Health Monitor supports this type of workflow by bringing engine-condition trends together with the maintenance history held in the M&E environment, allowing engineers to review developing changes in the context of what has already happened to the engine.
Condition-Based Maintenance and Reliability Engineering
Condition monitoring and reliability analysis are closely related.
A condition signal may indicate that an individual asset deserves attention, while reliability analysis helps Engineering understand whether similar behaviour is appearing across aircraft, systems or components.
Defects, unscheduled removals, utilisation and maintenance findings can therefore provide important context around a developing condition trend.
Explore how EXSYN supports this wider analysis through Reliability Intelligence.
Condition-Based Maintenance vs Predictive Maintenance
Condition-based maintenance and predictive maintenance are related, but they are not identical.
CBM responds to the current observed condition of an asset. When monitoring shows deterioration or movement outside an expected range, Engineering investigates whether maintenance action is required.
Predictive maintenance goes a step further by using historical and current information to estimate how a condition may develop in the future or when failure risk may increase.
Both approaches depend heavily on the quality and continuity of the underlying operational information.
Learn more in our glossary definition of Predictive Maintenance.
