The Constant Speed Drive maintains a constant RPM for which component?

The Constant Speed Drive maintains a constant RPM for which component?

• A. IDG
• B. APU
• C. Main Engine
• D. Electrical Bus

Answer: (A)

Constant speed drive keeps the electrical system stable by holding the generator’s shaft at a constant speed so the output frequency stays steady. It’s connected to the Integrated Drive Generator, so the generator runs at a fixed RPM regardless of engine speed. This is essential because engine RPM varies in flight, and without the CSD the generator frequency would swing, affecting avionics and electrical systems. The other components—the APU, the main engine, and the electrical bus—aren’t what the CSD regulates; the APU has its own drive, the main engine drives the accessory gear train, and the electrical bus is just the distribution path powered by the generators.

Constant speed drive keeps the electrical system stable by holding the generator’s shaft at a constant speed so the output frequency stays steady. It’s connected to the Integrated Drive Generator, so the generator runs at a fixed RPM regardless of engine speed. This is essential because engine RPM varies in flight, and without the CSD the generator frequency would swing, affecting avionics and electrical systems. The other components—the APU, the main engine, and the electrical bus—aren’t what the CSD regulates; the APU has its own drive, the main engine drives the accessory gear train, and the electrical bus is just the distribution path powered by the generators.