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A fuel discharge tube, connected to the fuel nozzle filter.

-An electrical wiring harness, connected to the ECU.
There are two types of fuel flow transmitter available.
The first type consists of an aluminium body with a cylindrical bore. An electrical connector is installed on the outside of a
rectangular electronics compartment. The fuel flow transmitter consists of:
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 A driver assembly.

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 A flow straightener.

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 A measurement assembly.

-2 pickoff coils.

EFG

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EFFECTIVITY ALL CFM56-5B ENGINES FOR A319-A320-A321 CFMI PROPRIETARY INFORMATION . CTC-201-281-00
 73-30-11 ENGINE SYSTEMS  Page 3 Jan 03 

CFM56-5B TRAINING MANUAL

EFG
FUEL FLOW TRANSMITTER
The driver assembly, flow straightener and measurement assembly are put on a shaft and installed in the bore.

The transmitter driver assembly is made up of a shrouded turbine, petal valves and a valve support cone.
Fuel enters the turbine and flows out through angled drive holes and this causes the driver to rotate, thus turning the measurement assembly which is installed on the same shaft.
Bypass holes, covered by petal valves, control driver speed at high fuel flow rates, limiting the transmitter rotational speed.
After the fuel leaves the driver assembly, it goes through a flow straightener, which is stationary and not attached to the shaft. The straightener removes all swirl and other disturbances in the fuel flow.

The measurement assembly consists of an impeller and a drum. The drum is on the same shaft as the driver and so, turns at the same rate.
The impeller is installed on the shaft, on bearings. It is attached to the drum through a spring assembly and is turned only by the spring. This permits impeller movement with respect to the attached parts.
As the spring assembly tries to turn the impeller, the impeller, in turn, tries to rotate the fuel flow and the spring that drives the impeller deflects, permitting a rotational deflection between the drum and impeller. The deflection angle between the drum and impeller provides a measurement of fuel flow mass.
The drum and impeller each have 2 magnets installed in them, on opposite sides (180° apart). As the drum and impeller turn, the magnets generate an electrical pulse in the pickoff coils as they pass. The time between drum pulse and impeller pulse defines the deflection and is proportional to the fuel flow.
The pulses are supplied to the fuel flow indicator where they are changed to a mass flow measurement.

EFG

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CTC-201-282-02
　
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