Hot Section Inspection (HSI)

A Hot Section Inspection examines the combustion and turbine area of a gas-turbine engine — the parts running hottest and under the most stress — usually at a defined interval between overhauls. Like TBO status, where an engine sits relative to its next HSI affects both value and expected maintenance cost.

Why it matters: on many turbine engines the hot section — combustion and turbine components living at extreme temperature — is inspected around the midpoint of the overhaul interval. It is both a meaningful cost event and the best available window into how the engine has been treated.

A clean hot-section result signals disciplined operation and supports value; findings foreshadow the cost of the eventual overhaul. Buyers evaluating turbine aircraft should establish where each engine sits relative to its next hot section and overhaul, and whether recent inspection results are documented — these positions translate directly into price.