timetorepair

Time to repair (TTR) is a reliability and maintenance metric that measures the duration required to restore a system or component to full operation after a failure. It generally refers to the time from failure detection or reporting to the moment the system is confirmed functioning again. Definitions can vary: some include diagnostic and testing time, while others focus only on the on-site repair work.

Mean time to repair (MTTR) is the average TTR observed over a period or across incidents. It is calculated by dividing the total repair time by the number of repair events. TTR is commonly analyzed alongside other reliability metrics such as mean time between failures (MTBF) to assess maintainability and to estimate system availability. A common availability expression is MTBF / (MTBF + MTTR), under steady-state assumptions.

Applications of TTR include maintenance planning, service level agreement (SLA) commitments, and resource allocation for technicians and spare parts. Reducing TTR typically involves preventive maintenance, faster diagnostics, standardized repair procedures, improved on-site access to skilled labor, and reliable parts supply chains.

Limitations include variability across incident types, environments, and how TTR is measured, which can complicate comparisons. Clear definitions of start and end points and consistent data collection are essential for meaningful analysis. Related terms you may encounter include MTTR, MTBF, and MTTF (mean time to fail).