FAA Powerplant Written Practice Test

What is the first engine instrument indication of a successful start of a turbine engine?

1. Increase in fuel pressure

2. Decrease in exhaust gas temperature

3. Rise in exhaust gas temperature

4. Decrease in engine rpm

The correct answer is: Rise in exhaust gas temperature

The rise in exhaust gas temperature (EGT) is indeed the first engine instrument indication of a successful start of a turbine engine. When the engine begins to start, fuel is introduced into the combustion chamber, where it ignites and causes the temperature of the exhaust gases to increase. This rise in EGT signifies that combustion is occurring as expected, indicating a successful engine start. Monitoring EGT is crucial during the start-up sequence because it allows operators to confirm that the engine is transitioning from the start phase into normal operation. A rise in EGT will typically be one of the first indications seen on the engine instruments once combustion has initiated. In contrast, an increase in fuel pressure typically occurs before ignition and does not confirm a successful start. A decrease in exhaust gas temperature would suggest that the combustion process is failing or that the engine is cooling down, which would not indicate a successful start. Similarly, a decrease in engine rpm would imply that the engine is not developing sufficient speed, which is contrary to what is expected during a successful start. Therefore, the rise in exhaust gas temperature is the clear indicator of successful combustion and engine start-up in turbine engines.