Definition
The manufacturer's recommended operating time, measured in flight hours, between major overhauls of an engine, propeller, or other component. At the end of this interval, the manufacturer recommends the component be disassembled, inspected, and restored to a defined service condition before further use.
Plain English
How many hours the maker says an engine or component should run before it is taken apart, inspected, and rebuilt back to as-good-as-new condition.
Context Anchor
Seen in aircraft maintenance records, engine logbooks, propeller records, aircraft purchase inspections, and maintenance planning.
Derivation
“Overhaul” comes from the idea of hauling something over, or taking it apart and going through it carefully. That helps the aviation meaning: the component is not just checked quickly; it is thoroughly inspected and restored as needed.
Why Pilots Care
It sets the schedule for major maintenance to keep the engine safe and reliable.
Intuition Check
Do not read Time Between Overhauls as the exact moment a part will fail. It is a recommended maintenance interval, and whether it is legally required depends on the aircraft, the operation, and any specific rules that apply.
Example Sentence 1
The Lycoming engine has a 2,000-hour TBO, and with 1,850 hours on the tach, the buyer factored an upcoming overhaul into the purchase price.
Example Sentence 2
The pilot reviewed the time between overhauls listed in the manual before scheduling the annual inspection.