Which turbine drives the compressor in a gas turbine engine?

• A. Gas generator
• B. Power turbine
• C. Starter motor
• D. Accessory gearbox

Answer: (A)

In a gas turbine engine, the compressor is driven by the turbine on the gas generator side, the high‑pressure turbine that sits on the same shaft as the compressor. When fuel is burned in the combustor, the expanding gases pass through this turbine, extracting energy to turn the shaft and, in turn, the compressor. The power turbine (if present) is on a separate shaft and provides shaft power to a load rather than driving the compressor. The starter motor is only used to start the engine, not to run it once it’s started. The accessory gearbox is driven by the gas generator shaft to run pumps and other accessories, but it isn’t the turbine that powers the compressor itself.