Which instrument uses a thermocouple system to measure temperature?

• A. Cylinder-head temperature and exhaust gas temperature
• B. Oil pressure gauge
• C. Fuel flow indicator
• D. Manifold pressure gauge

Answer: (A)

Thermocouples produce a small voltage that is proportional to temperature, allowing accurate measurement in very hot areas. In aviation engines, cylinder-head temperatures and exhaust gas temperatures are monitored with thermocouples because these locations run at high, dynamic temperatures and need quick, robust sensing. The sensors are placed in or near the cylinder head for CHT and in the exhaust stream for EGT, with the generated millivolt signal fed to the gauge or engine monitoring system.

The oil pressure gauge, fuel flow indicator, and manifold pressure gauge rely on pressure or flow sensing methods rather than temperature sensing, so they do not use a thermocouple system.