What is MTBUR in Aviation? (Mean Time Between Unscheduled Removals)

Mean time between unscheduled removals (MTBUR) is a key performance indicator used in the aviation industry to measure the reliability of aircraft systems and components. It represents the average amount of time that elapses between two consecutive unscheduled removals of a particular part or component.

In simpler terms, MTBUR is a measure of how long an aircraft system or component can operate without experiencing a failure or breakdown that requires it to be removed and repaired or replaced. It is an important metric for aviation maintenance professionals as it helps them assess and improve the reliability and performance of aircraft systems and components.

MTBUR is typically expressed in hours and is calculated by dividing the total operating time of a system or component by the number of unscheduled removals within that period. For example, if a particular component has been in operation for 1,000 hours and has been removed twice due to unscheduled failures, the MTBUR for that component would be 500 hours.

MTBUR is an essential metric in aviation maintenance as it allows maintenance teams to identify systems or components with low reliability and target them for improvement. By analyzing the MTBUR of different parts and systems, maintenance professionals can determine which components are more prone to failures and take proactive measures to reduce the likelihood of those failures occurring.

MTBUR is also used to establish maintenance schedules and plan maintenance activities. By knowing the average time between unscheduled removals for various components, maintenance teams can anticipate when a particular part is likely to fail and plan maintenance tasks accordingly to minimize disruptions and downtime.

Factors Affecting Mean time between unscheduled removals (MTBUR)

Several factors can impact the MTBUR of aircraft systems and components. Here are some of the key factors that can affect MTBUR:

Component Quality and Manufacturing

The quality and manufacturing of a component can play a significant role in its reliability and MTBUR. Components that are manufactured with higher quality materials and processes are generally more reliable and have longer MTBUR values. On the other hand, components that are prone to defects or manufacturing errors may have shorter MTBUR values and require more frequent removals for repairs or replacements.

It is crucial for aviation manufacturers to adhere to strict quality control standards and procedures to ensure that their components meet the necessary reliability requirements. Quality assurance processes and rigorous testing during the manufacturing phase can help identify and eliminate potential defects or issues that could impact the MTBUR of the components.

Maintenance Practices and Procedures

The maintenance practices and procedures implemented by an airline or maintenance organization can have a significant impact on MTBUR. Proper maintenance practices, such as regular inspections, preventive maintenance, and timely repairs, can help identify and address potential issues before they cause unscheduled removals.

Additionally, following manufacturer-recommended maintenance procedures and schedules can help ensure that components are maintained and replaced at the appropriate intervals, minimizing the risk of failures and unscheduled removals. Effective maintenance planning and execution can contribute to longer MTBUR values and improved overall reliability of aircraft systems and components.

Operating Conditions and Environment

The operating conditions and environment in which an aircraft operates can also impact the MTBUR of its systems and components. Harsh operating conditions, such as extreme temperatures, high altitudes, or exposure to corrosive substances, can accelerate wear and tear on components, leading to more frequent failures and unscheduled removals.

Furthermore, the maintenance of systems or components in environments with high levels of contamination, such as dust or debris, can also increase the likelihood of failures and reduce MTBUR. Proper environmental controls, maintenance procedures, and regular inspections can help mitigate the impact of operating conditions and environment on MTBUR.

Benefits of Monitoring and Improving Mean time between unscheduled removals (MTBUR)

Monitoring and improving the MTBUR of aircraft systems and components can provide several benefits for airlines and maintenance organizations:

Enhanced Reliability and Safety

By focusing on improving MTBUR, airlines and maintenance organizations can enhance the reliability and safety of their aircraft. Longer MTBUR values indicate that systems and components are less prone to failures and breakdowns, reducing the chances of in-flight issues and potential safety hazards.

Improved reliability and safety contribute to enhanced customer satisfaction, as passengers can trust that the aircraft they are flying on is well-maintained and less likely to experience technical issues during their journey.

Reduced Maintenance Costs

By increasing the MTBUR of aircraft systems and components, airlines and maintenance organizations can reduce maintenance costs. Longer MTBUR values mean fewer unscheduled removals and repairs, resulting in decreased maintenance labor and parts expenses.

Efficient maintenance planning and scheduling based on MTBUR data can also help minimize aircraft downtime and optimize maintenance resource allocation, further reducing costs associated with maintenance operations.

Improved Operational Efficiency

A higher MTBUR allows airlines to operate their aircraft more efficiently by reducing the frequency of unexpected maintenance disruptions. This leads to improved on-time performance and increased aircraft availability for commercial use.

By implementing measures to improve MTBUR, such as proactive maintenance and component reliability enhancements, airlines can enhance their operational efficiency and maximize the utilization of their aircraft fleet.


Mean time between unscheduled removals or MTBUR is an important metric in aviation maintenance. It helps measure the reliability of aircraft systems and components by calculating the average time between two consecutive unscheduled removals. Factors such as component quality, maintenance practices, and operating conditions can impact MTBUR.

By monitoring and improving MTBUR, airlines and maintenance organizations can enhance the reliability, safety, and efficiency of their aircraft operations. Longer MTBUR values result in enhanced customer satisfaction, reduced maintenance costs, and improved operational efficiency.

To optimize aircraft systems and components’ MTBUR, it is important to adhere to strict manufacturing standards, implement effective maintenance practices, and mitigate the impact of harsh operating conditions and environments. Through continuous monitoring and improvement, aviation industry stakeholders can strive for higher MTBUR values and ultimately achieve safer and more reliable air travel.

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