What action should be taken if a turbine engine starts to show signs of excessive temperature during start-up?

When a turbine engine exhibits signs of excessive temperature during start-up, the most appropriate action is to immediately shut down the engine. This course of action is critical to prevent potential damage to the engine components caused by overheating. High temperatures during the start sequence can indicate a malfunction, such as a fuel system issue or a problem with the engine's internal components. Shutting down the engine promptly helps to mitigate the risk of severe damage, ensuring the safety of the aircraft and its systems.

Continuing with the start sequence could exacerbate any existing issues, leading to further complications or catastrophic failure. Increasing fuel flow is counterproductive because it could heighten the temperature, worsening any problems. Reducing the throttle position does not address the underlying cause of the excessive temperature and might not effectively cool the engine. Therefore, immediate shutdown is the safest and most prudent action to take in this scenario.