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What a torque valve meters

Aviation Mechanic Powerplant (AMP) practice question 8 of 12 on Engine Instrument Systems. ACS element AM.III.D.K6 · 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 most torque indicating systems, what does the torque valve meter in proportion to the torque being produced?

  1. AFuel pressure at the nozzle
  2. BCompressor bleed air pressure
  3. CEngine oil pressure
Show the answer and explanation

Correct answer: C. Engine oil pressure

  • A — incorrect Fuel pressure is read by its own gauge and has no part in the torque measuring arrangement described.
  • B — incorrect Bleed air serves other systems; the torque valve works with the engine's oil pressure.
  • C — correct Most torque systems use an oil pressure output from a torque valve, which meters oil pressure in proportion to the torque produced.

BACKGROUND

A torquemeter indicates the amount of torque being produced at the propeller shaft, which is the actual power output at a given power setting. In most systems, a helical gear moves back and forth as shaft torque varies; acting on a piston, it positions a valve that meters oil pressure in proportion to the torque. A transducer connected to that valve converts the pressure change to an electrical signal transmitted to the flight deck. The readout can be expressed in foot-pounds of torque, in percent of horsepower, or in horsepower; earlier systems read in pounds per square inch (psi) and the flight engineer converted that figure to a power setting. Some installations instead use strain gauges attached to the ring gear to supply an electrical signal directly to the readout.

STUDY TIP

Remember the chain: helical gear to piston to torque valve to oil pressure to transducer to flight deck readout.

KEY POINTS

  • Most torque systems meter oil pressure through a torque valve.
  • A transducer converts that pressure to an electrical signal for the flight deck.
  • Readouts may be in foot-pounds, percent of horsepower, or horsepower.

SOURCES

  • FAA-H-8083-32B ch10 "Torquemeter"
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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.