Mean Time Between Overhaul
(Mean) Time Between Overhaul ( MTBO or TBO ) are synonymous English terms for the average time until the overhaul of devices, machines or engines . MTBO serves as a measure of the longevity of devices or systems.
The higher the MTBO value, the more durable the device should be. A device with an MTBO of 100 hours is therefore more likely to be due for overhaul than an otherwise comparable device with an MTBO of 1,000 hours.
example
With an aircraft engine, the TBO indicates the time until the engine has to be completely overhauled. For reciprocating engines , the TBO is between 1000 and 2500 hours. Various other checks must be carried out within this time, such as B. the 100-hour inspection or a 500-hour inspection, which may only be carried out by a certified aircraft mechanic. If the TBO period has expired, the engine must be taken to the manufacturer or to a specialist workshop approved for this purpose in order to be completely overhauled. In general, however, there is no obligation for non-commercially operated aircraft to have an engine overhauled after the TBO has expired. If the compression in one or more cylinders falls below a limit value that differs from engine to engine, or if a high proportion of metal chips is found in the oil during an oil change, the engine should be overhauled. Depending on how the engine is handled, the actual service life can deviate from the specified TBO by several 100 hours.
For aircraft in commercial operation, however, the TBO is binding and indicates the maximum number of operating hours until the overhaul.