Which indicator shows no ITT increase after an engine start attempt?

The indicator that shows no ITT (Inter-Turbine Temperature) increase after an engine start attempt is indicative of a "No Light Off" condition. When an engine start is initiated, the expectation is that the combustion process will light off and initiate a rise in ITT due to increasing temperatures from the combustion of fuel. If there is no increase in ITT, it suggests that the fuel is not igniting as expected, which is defined as a "No Light Off" situation.

This condition can point to several issues, such as a lack of fuel delivery, an absence of sufficient airflow, or a malfunction within the ignition system. Engineers and pilots utilize this indicator to assess the health of the engine post-start attempt. Recognizing a "No Light Off" event is critical, as it can lead to further diagnostic checks or shut down of the engine if necessary to avoid any potential damage or hazards.

Understanding this indicator helps ensure proper engine operation and safety protocols are maintained during start attempts and is essential for effective troubleshooting in the cockpit.