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Component required by duplex fuel nozzles

Aviation Mechanic Powerplant (AMP) practice question 2 of 20 on Engine Fuel and Fuel Metering Systems. ACS element AM.III.I.K7 · 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 equipped with duplex fuel nozzles requires which additional component that a simplex installation does not?

  1. AA flow divider or pressurizing valve
  2. BA second engine-driven fuel pump
  3. CAn air-to-liquid fuel heater in the line
Show the answer and explanation

Correct answer: A. A flow divider or pressurizing valve

  • A — correct The duplex nozzle usually requires a dual manifold plus a pressurizing valve or flow divider to separate primary and secondary fuel flow, while the simplex nozzle needs only a single manifold.
  • B — incorrect Both nozzle types are fed by the same engine-driven pump; the dual flow paths are created by dividing the metered fuel, not by adding another pump.
  • C — incorrect A fuel heater protects the fuel filter from ice and is not related to nozzle configuration; simplex and duplex installations may both use one or neither.

BACKGROUND

Fuel nozzles spray fuel into the combustion area in a highly atomized, precisely patterned spray so that burning is completed evenly and in the smallest possible space. The two types generally used are the simplex and duplex configurations. The simplex nozzle was the first type used in turbine engines and needs only a single manifold for proper fuel delivery. The duplex nozzle produces two different spray patterns and therefore usually requires a dual manifold along with a pressurizing valve or a flow divider to split primary and secondary flow. The duplex arrangement gives better atomization at starting and idling speeds and a desirable spray pattern over a wide range of operating pressures.

STUDY TIP

Link the number of spray patterns to the number of manifolds: one pattern means one manifold, two patterns mean two manifolds plus something to divide the flow. Note that a flow divider and a pressurizing valve perform essentially the same function under different names.

KEY POINTS

  • Simplex nozzles need only a single fuel manifold.
  • Duplex nozzles need a dual manifold plus a flow divider or pressurizing valve.
  • Duplex nozzles give better atomization at starting and idling speeds.

SOURCES

  • amp-powerplant/ch02.txt "Fuel Spray Nozzles & Fuel Manifolds"
  • amp-powerplant/ch02.txt "Fuel Pressurizing & Dump Valves"
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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.