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Low-pressure spool of a two-spool turbofan

Aviation Mechanic Powerplant (AMP) practice question 11 of 13 on Turbine Engines. ACS element AM.III.B.K2 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONIn a two-spool turbofan engine, which components make up the low-pressure spool?

  1. AThe fan and the turbine stages that drive it
  2. BThe fan, the combustion section, and its turbines
  3. CThe high-pressure compressor and its turbines
Show the answer and explanation

Correct answer: A. The fan and the turbine stages that drive it

  • A — correct The low-pressure spool generally contains the fan or fans along with the turbine stages required to drive them.
  • B — incorrect The combustion section is located in the core, which is the high-pressure spool, not the low-pressure spool.
  • C — incorrect The high-pressure compressor, its shaft, and its turbines make up the high-pressure spool, which forms the core of the engine.

BACKGROUND

A spool is a compressor together with a shaft and the turbines that drive that compressor. Turbofan engines have more than one shaft, and many are two-shaft engines with two sets of compressors and the turbines that drive them. In a two-spool engine there is a high-pressure spool and a low-pressure spool, each turning independently at its own speed. The high-pressure spool makes up the core of the engine, and the combustion section is located there. Tachometer indications for these spools are usually labeled N1 and N2, each with its own indicator.

STUDY TIP

Anchor the definition of a spool first: compressor plus shaft plus the turbines that turn it. Then remember that the core, including the burner, always belongs to the high-pressure spool.

KEY POINTS

  • A spool is a compressor, its shaft, and the turbines that drive that compressor.
  • The low-pressure spool carries the fan and the turbine stages that drive it.
  • The high-pressure spool forms the engine core and contains the combustion section.

SOURCES

  • FAA-H-8083-32B ch01 "Gas Turbine Engines, Types & Construction"
  • FAA-H-8083-32B ch10 "Tachometer"
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON TURBINE ENGINES

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.