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Heat sources for a turbine engine fuel heater

Aviation Mechanic Powerplant (AMP) practice question 16 of 20 on Engine Fuel and Fuel Metering Systems. ACS element AM.III.I.K11 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONA turbine engine fuel heater operates as a heat exchanger. Which sources of heat does it use?

  1. AExhaust gas or hydraulic fluid
  2. BEngine bleed air or lubricating oil
  3. CCompressor inlet air or ram air ducting
Show the answer and explanation

Correct answer: B. Engine bleed air or lubricating oil

  • A — incorrect Neither exhaust gas nor hydraulic fluid is listed as a heat source for the fuel heater; the two recognized sources are bleed air and lubricating oil.
  • B — correct The heater can use engine bleed air, making it an air-to-liquid exchanger, or engine lubricating oil, making it a liquid-to-liquid exchanger.
  • C — incorrect The only air source named for heating the fuel is engine bleed air, so air taken at the compressor inlet or through a ram air duct does not apply.

BACKGROUND

Gas turbine engine fuel systems are very susceptible to the formation of ice in the fuel filters. When fuel in the tanks cools to 32 degrees Fahrenheit or below, residual water tends to freeze into ice crystals that can become trapped in the filter and block fuel flow. To prevent this, the fuel is kept above freezing by a fuel heater that works as a heat exchanger. The heater can use engine bleed air, in which case it is an air-to-liquid exchanger, or engine lubricating oil, in which case it is a liquid-to-liquid exchanger. Fuel deicing systems are designed to be used intermittently and may be controlled manually from the flight deck or automatically by a thermostatic sensing element in the heater.

STUDY TIP

Remember the two names along with the two sources: air-to-liquid for bleed air and liquid-to-liquid for oil. Also note that the heater can thaw ice already on the screen, not just prevent it.

KEY POINTS

  • Fuel heaters prevent ice crystals from blocking turbine engine fuel filters.
  • Heat comes from engine bleed air (air-to-liquid) or lubricating oil (liquid-to-liquid).
  • Fuel deicing systems are intended for intermittent use, manually or thermostatically controlled.

SOURCES

  • amp-powerplant/ch02.txt "Fuel Heater"
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON ENGINE FUEL AND FUEL METERING 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.