Aircraft Temperature Sensing: Scale Conversion and CSD Monitoring

022-01-02Pablo Asensio Martínez2026-04-011 min

Temperature measurement in aviation is essential for monitoring systems like engines and generators, as well as for atmospheric data.

Temperature Conversion

Pilots and engineers must be able to convert between different temperature scales: Celsius (°C), Fahrenheit (°F), and Kelvin (K).

The relevant formulas are:

Fahrenheit to Celsius: $^\circ F = 1.8 \times (^\circ C) + 32$
Kelvin to Celsius: $K = ^\circ C + 273$ (or $^\circ C = K - 273$)

For example, a temperature of 20°C converts to 68°F ($1.8 \times 20 + 32$) and 293 K ($20 + 273$). Note that 0°C corresponds to 273 K.

Application: Constant Speed Drive (CSD)

Temperature sensing is critical for the Constant Speed Drive (CSD) unit. The CSD is a hydraulic-mechanical device that regulates the generator's speed to ensure a constant output frequency, regardless of engine speed changes. It connects to the engine via a dog clutch.

Monitoring: The cockpit provides warnings if the CSD oil temperature is too high (often accompanied by low oil pressure/level).
Action: In such cases, pilots can disconnect the CSD in flight to prevent damage. Once disconnected, it cannot be re-engaged in the air and requires maintenance on the ground.