What malfunction is indicated by no rise in ITT or N1 within ten seconds of rotating the twist grip to IDLE?

• A. Slow start
• B. Ignition failure
• C. Quick start
• D. Hot start

Answer: (B)

The indication of no rise in Interpreted Turbine Temperature (ITT) or N1 within ten seconds of rotating the twist grip to IDLE strongly points to an ignition failure. In a properly functioning turbine engine, when the throttle is moved to the IDLE position, the engine should respond within a short timeframe by indicating a rise in ITT and N1 as the fuel is ignited and the engine begins to spool up.

A delay in these indicators beyond the established timeframe signals that the ignition system has likely failed to initiate combustion within the engine. Ignition failure can prevent the proper operation of the turbine engine, leading to a lack of thrust and potential engine shutdown. This understanding is essential for pilots and technicians, as recognizing this type of malfunction could lead to necessary immediate action, such as an aborted start or securing the engine.

In contrast, conditions like a slow start, quick start, or hot start are associated with different operational parameters and behaviors during the start sequence, none of which would align with the specific symptom of no ITT or N1 rise within the initial ten seconds of starting the engine.