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Inlet lip ice protection on a high-bypass turbofan

Aviation Mechanic Powerplant (AMP) practice question 3 of 9 on Turbine Engine Air Systems. ACS element AM.III.K.K8 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONHow is the inlet lip of a high-bypass turbofan engine protected against ice formation?

  1. AWarm bleed air is circulated in the lip
  2. BExhaust gas is ducted forward to the lip
  3. CA rubber boot on the lip is inflated
Show the answer and explanation

Correct answer: A. Warm bleed air is circulated in the lip

  • A — correct Warm air bled from the engine's compressor is drawn off and circulated on the inside of the inlet lip to keep ice from forming.
  • B — incorrect Exhaust gas is not routed forward to the inlet; the anti-icing air comes from the compressor as bleed air.
  • C — incorrect The rubber component inside a turbofan inlet is the abradable rub strip at the fan blade tips, which has nothing to do with ice protection.

BACKGROUND

On most modern turbofan engines the large fan is the first part of the aircraft that incoming air contacts, so ice protection must be provided. Without it, chunks of ice could form on the leading edge of the inlet, break loose, and damage the fan. Warm bleed air is drawn from the engine's compressor and circulated on the inside of the inlet lip for anti-icing, and if inlet guide vanes are fitted they also receive anti-icing air. The fan hub or spinner is either heated by warm air or made conical so ice cannot build up on its surface. By contrast, the inlets of many turboprops are anti-iced with electrical elements in the lip opening, and deflector doors and inlet screens may be used to keep ice and debris out of the intake.

STUDY TIP

Keep the two methods separate in your memory: turbofan inlet lips use warm compressor bleed air, while many turboprop intake lips use electrical heating elements.

KEY POINTS

  • Turbofan inlet lips are anti-iced with warm compressor bleed air circulated inside the lip.
  • Inlet guide vanes also receive anti-icing air, and spinners are heated or made conical.
  • Many turboprop inlets instead use electrical elements in the lip, plus deflector doors and screens.

SOURCES

  • amp-powerplant ch03 "Turbofan Engine Inlet Sections"
  • amp-powerplant ch01 "Air Entrance"
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON TURBINE ENGINE AIR SYSTEMS

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.