What does CSD stand for?

• A. Constant Source Drive
• B. Current Speed Drive
• C. Control Speed Device
• D. Constant Speed Drive

Answer: (D)

CSD stands for Constant Speed Drive, a device used in aircraft to keep a generator running at a steady speed even as the engine speed varies. This steady generator speed preserves a constant electrical frequency and voltage, which is essential for avionics and systems that rely on stable power. The other terms don’t fit established aviation terminology because they imply something different or nonstandard, whereas Constant Speed Drive precisely describes the mechanism that regulates the generator’s speed to match the electrical requirements.