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Turbine fuel-flow indicator units

Aviation Mechanic Powerplant (AMP) practice question 3 of 12 on Engine Instrument Systems. ACS element AM.III.D.K1 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONIn most turbine aircraft installations, the fuel-flow indicator is calibrated to read the fuel flow in what units?

  1. AGallons of fuel per hour
  2. BPounds of fuel per hour
  3. CPercent of rated fuel flow
Show the answer and explanation

Correct answer: B. Pounds of fuel per hour

  • A — incorrect Gallons per hour is the unit given for the direct-reading, volume-based flow measurement used with reciprocating engines, not for the turbine installation.
  • B — correct The powerplant handbook states that on turbine aircraft the indicator is calibrated to record fuel flow in pounds of fuel per hour.
  • C — incorrect Percent scales are used for turbine engine speed indicators, not for the fuel-flow indicator, which reads an actual rate.

BACKGROUND

A fuel-flow meter measures the amount of fuel actually delivered to the engine, which is a direct check on whether the engine is receiving the correct air-fuel mixture for a given power setting. In most turbine aircraft the system consists of a transmitter and an indicator for each engine. The transmitter is mounted in the engine's accessory section and measures the flow between the engine-driven fuel pump and the fuel control device; it contains a turbine that spins faster as flow increases, raising the electrical signal sent to the indicator. Because turbine engine performance depends on fuel mass rather than volume, the turbine indicator is calibrated in pounds of fuel per hour. Volume-based flow figures for reciprocating engine testing are normally expressed in gallons per hour.

STUDY TIP

Fix the pairing in your mind: turbine fuel flow is read in pounds per hour, while volume-based reciprocating measurements are read in gallons per hour.

KEY POINTS

  • Turbine fuel-flow indicators read in pounds of fuel per hour.
  • The transmitter sits between the engine-driven fuel pump and the fuel control device.
  • A turbine inside the transmitter spins faster with flow, increasing the signal to the indicator.

SOURCES

  • FAA-H-8083-32B ch10 "Fuel-Flow Meter"
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MORE ON ENGINE INSTRUMENT 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.