Which parameter represents the speed of the high pressure spool?

Which parameter represents the speed of the high pressure spool?

• A. Speed of High Pressure Spool
• B. Speed of Low pressure spool
• C. 7 bearings
• D. 61.5%

Answer: (A)

The speed of the high pressure spool is the parameter that directly describes how fast the inner core compressor shaft is turning. In a two-spool engine, the high pressure spool drives the core compression and operates at a much higher RPM than the low pressure spool. This HP spool speed is the measurement used by engine control systems to regulate fuel flow and maintain stable operation, since it reflects the core’s performance and surge margin. The speed of the low pressure spool would be a different rotor speed, the number of bearings isn’t a rotational speed, and a percentage like 61.5% isn’t a direct measure of HP spool RPM.

The speed of the high pressure spool is the parameter that directly describes how fast the inner core compressor shaft is turning. In a two-spool engine, the high pressure spool drives the core compression and operates at a much higher RPM than the low pressure spool. This HP spool speed is the measurement used by engine control systems to regulate fuel flow and maintain stable operation, since it reflects the core’s performance and surge margin. The speed of the low pressure spool would be a different rotor speed, the number of bearings isn’t a rotational speed, and a percentage like 61.5% isn’t a direct measure of HP spool RPM.