FAA Powerplant Written Practice Test

Where are the highest heat to metal contacts found in a jet engine?

1. Turbine inlet nozzle vanes

2. Compressor blades

3. Combustion chamber walls

4. Exhaust nozzle

The correct answer is: Turbine inlet nozzle vanes

The highest heat to metal contacts in a jet engine are found in the turbine inlet nozzle vanes. These vanes are located at the entrance of the turbine section and are responsible for directing the high-temperature, high-pressure exhaust gases from the combustion chamber into the turbine blades. As the gases exit the combustion chamber, they can reach extremely high temperatures due to the combustion of fuel and air. The turbine inlet nozzle vanes must withstand this intense thermal environment while also maintaining structural integrity and aerodynamic efficiency. The materials used in these vanes are specially designed to endure high temperatures and thermal stress. In contrast, while the compressor blades and combustion chamber walls do experience significant heat, they do not reach the same thermal extremes as the turbine inlet nozzle vanes. The exhaust nozzle also handles hot gases, but it is downstream of the turbine and does not have the same level of direct contact with the heat generated in the combustion chamber. Therefore, in terms of direct exposure to high-temperature gases, the turbine inlet nozzle vanes are where the highest heat to metal contact occurs in a jet engine.