What parameter does a thermocouple provide an electrical signal for?

• A. Exhaust gas temperature
• B. Engine RPM
• C. Ambient air humidity
• D. Fuel pressure

Answer: (A)

A thermocouple is a temperature sensor that generates an electrical signal whose voltage is proportional to temperature, using the Seebeck effect. In aviation engines, it’s used to measure exhaust gas temperature, giving a direct electrical signal that represents how hot the exhaust is. This temperature data helps monitor engine performance and prevent overheating by guiding fuel control and launch limits.

The other options don’t fit because they measure different quantities with different sensors: engine RPM is read with tach or magnetic pickups, ambient humidity uses a humidity sensor, and fuel pressure is read with a pressure transducer. None of these rely on a thermocouple’s voltage produced from temperature.