190-01115-01 G3X™/G3X Touch™ Avionics Installation Manual
Rev. AV Page 21-32
21.3.9.2 Hall Effect Current Sensor
Hall Effect current sensors can be used to sense electrical current through induced magnetic fields, without
direct connection to high-current conductors.
The default Hall Effect current sensor supported by the G3X system is the AMPLOC KEY100. This sensor
outputs 2.5V at zero amps, with a sensitivity of 15.9 mV/Amp up to +/- 100A. Other Hall Effect sensors
with different specifications can be supported using calibration adjustments. See Current portion of
Appendix H.4.19.3.2
for GDU 37X systems and Section 30.4.32.15 for GDU 4XX systems for
configuration guidance.
21.3.10 Fuel Flow
Fuel flow in the G3X system is sensed using a mechanical transducer which converts the movement of fuel
to a series of digital pulses.
For engines with a fuel return line, a second flow sensor must be used to measure the quantity of unused
fuel that is returned from the engine to the fuel tank. Connect the return fuel flow sensor to the GEA 24/
GSU 73 FUEL FLOW 2 input (see Figure
30-2.1). The value displayed on the fuel flow gauge will be the
difference between the main (supply) fuel flow and secondary (return) fuel flow measurements.
21.3.10.1 K-Factor Adjustment
The number of electrical pulses sensed per gallon of fuel flow is referred to as the K-Factor. The G3X
system uses the configured K-Factor to convert pulse frequency to fuel flow. When installing the fuel flow
sensor, the installer should take note of number on the tag attached to the sensor (if applicable). This
number is the calibrated K-Factor of the sensor. For sensors that are not supplied with a specific calibration
value, use the default K-Factor value provided.
Although each fuel flow sensor has a default K-Factor value, aspects unique to each installation will affect
the accuracy of the initial K-Factor, and as a result the K-Factor must generally be adjusted up or down for
accurate fuel flow measurement.
If the fuel usage reported by the G3X system differs from the actual fuel usage, as measured at the fuel
pump (or other trusted method of measurement), use the following formula to calculate a corrected
K-Factor, which can then be used to calibrate the fuel flow.
Corrected K-Factor = ( [G3X reported fuel used] x [previous K-factor] ) / [actual fuel used]
Refer to the K-Factor portion of Appendix H.4.19.4
for (GDU 37X) or Section 30.4.32.13 (for GDU 4XX)
for information on entering K-Factor calibration.
21.3.10.2 Electronics International Fuel Flow Sensor Installation
Garmin sensor kits include the Electronics International FT-60 “red cube” fuel flow sensor (Garmin P/N
494-10001-00). Refer to Electronics International document # 1030032 for FT-60 installation guidance.
The default K-Factor for the FT-60 is 68,000 pulses/gallon. No sensor specific calibration is required for
the FT-60, but variations in the installation can affect the K-Factor as described above.
Other Electronics International FT-series fuel flow sensors are also supported; consult the manufacturer for
installation guidance.
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