In the dual axial-flow or twin-spool compressor system, the first stage turbine drives the N(2) compressor.

In the dual axial-flow or twin-spool compressor system, the first stage turbine drives the N(2) compressor.

• A. The N2 compressor.
• B. The N1 compressor.
• C. The accessory gearbox.
• D. The fuel pump.

Answer: (A)

In a twin-spool engine, two separate shafts run the compressors and turbines: the high-pressure side powers the high-pressure compressor (N2) and the low-pressure side powers the low-pressure compressor (N1). The first stage of the high-pressure turbine provides the energy to drive the high-pressure compressor, so the N2 compressor is what the first stage turbine drives. The low-pressure turbine drives N1, and the accessory gearbox and fuel pump are not described by this turbine stage driving the compressor. So the correct match is the N2 compressor.

In a twin-spool engine, two separate shafts run the compressors and turbines: the high-pressure side powers the high-pressure compressor (N2) and the low-pressure side powers the low-pressure compressor (N1). The first stage of the high-pressure turbine provides the energy to drive the high-pressure compressor, so the N2 compressor is what the first stage turbine drives. The low-pressure turbine drives N1, and the accessory gearbox and fuel pump are not described by this turbine stage driving the compressor. So the correct match is the N2 compressor.