Glossary
What is TBO?
Time between overhaul: an interval specified by the engine manufacturer, potentially expressed in operating hours and calendar time. It differs from time since overhaul, which records elapsed use after an overhaul. Find the applicable interval using the exact engine model, serial number, configuration and current maintenance documents. Do not assume one figure applies to all engines in a family. A qualified maintainer should establish what is recommended and what is mandatory for the individual aircraft and operation.
Also called Time between overhaul, time before overhaul
That is the whole entry for now. The longer version, with the mechanics and worked examples, is still to be written. See autorotation for how those read once they exist.