What is TIT/ITT and what happens if it exceeds limits?

• A. TIT/ITT stands for Turbine Inlet Temperature or Inter Turbine Temperature; exceeding limits causes thermal damage, accelerated creep, and possible engine shutdown or reduced power.
• B. TIT/ITT stands for Temperature in Turbine; exceeding limits causes only minor wear.
• C. TIT/ITT stands for Turbine Internal Temperature; exceeding limits improves efficiency.
• D. TIT/ITT stands for Total Idle Time; exceeding limits causes no issues.

Answer: (B)

The concept tested is how hot the turbine hot section can safely run. TIT (Turbine Inlet Temperature) and ITT (Inter-Turbine Temperature) are measurements of the air-hot gas temperature entering the turbine or between turbine stages. These temperatures are set because the turbine blades, nozzles, and other hot-section parts are cooled and made from materials that can only withstand so much heat for a given time.

If TIT/ITT exceeds their limits, the components in the hot section experience excessive thermal stress and creep, which accelerates wear and can cause cracks or material failure. That integrity loss can shorten component life, reduce engine reliability or performance, and, to protect the engine, the control system may derate the engine or shut it down to prevent a catastrophic failure.

The other options aren’t correct because TIT/ITT are not simply a vague “temperature in the turbine,” nor do higher-than-limit temperatures improve efficiency; nor is “Total Idle Time” a relevant measure.