Which parameter is most critical for a turbine engine during the starting phase?

During the starting phase of a turbine engine, the Exhaust Gas Temperature (EGT) is a critical parameter to monitor. This is because EGT is an essential indicator of engine performance and health during the initial moments of ignition and acceleration.

As the engine starts, it transitions from a state of no combustion to a fully operational state. Monitoring EGT helps ensure that the engine is burning the fuel efficiently and that the temperatures remain within safe limits. An overly high EGT can indicate a problem such as excessive fuel flow or inadequate airflow, which can lead to potential engine damage. Conversely, if the EGT is too low, it may indicate that the engine is not achieving the desired combustion status, which can result in a failed start or insufficient engine performance.

While oil pressure, alternative fuel flow, and compressor RPM are also important parameters, they do not directly reflect the immediate combustion and thermal characteristics of the engine during the start. Oil pressure is vital for lubrication but primarily of concern once the engine is operating. Alternative fuel flow is relevant when considering fuel types but is not critical during the initial start phase itself. Compressor RPM is necessary for engine stability, yet it is EGT that offers the most direct insight into the engine's combustion process at startup.