Definition
The manufacturer's recommended operating time, expressed in hours of service, between major overhauls of an aircraft engine or component. It represents the interval at which the manufacturer expects the engine to be disassembled, inspected, and restored to a serviceable condition before continued use.
Plain English
How many flight hours an engine is expected to run before it should be taken apart, inspected, and rebuilt. It is the manufacturer's recommended life span between major rebuilds.
Context Anchor
Seen in engine logbooks, maintenance records, aircraft sales listings, and maintenance planning discussions.
Derivation
“Overhaul” comes from the older idea of hauling something over for a thorough examination. In aviation maintenance, it means more than a quick check: the part is opened up, inspected deeply, repaired as needed, and tested.
Why Pilots Care
Operating beyond the published TBO without approved extensions risks engine failure and violates airworthiness requirements.
Intuition Check
TBO is not a guarantee that an engine will last that long, and it is not always an automatic legal deadline. It is a recommended overhaul interval that must be interpreted with the aircraft’s maintenance rules, records, and operating use.
Example Sentence 1
The engine has 1,400 hours since new and a TBO of 2,000 hours, so there are roughly 600 hours of recommended service remaining.
Example Sentence 2
The mechanic checked the hobbs meter to see how many hours remained before the next TBO.