Fuel Quantity; Resistive Type Fuel Quantity Sensors; Capacitive Type Fuel Quantity Sensors; Tit (Turbine Inlet Temperature) Sensor - Garmin G3X Installation Manual

14.3.6 Fuel Quantity

14.3.6.1 Resistive Type Fuel Quantity Sensors

Resistive type fuel quantity sensors with a 0–500 Ω range are currently supported. Wiring methods vary
based on the GEA 24/GSU 73 channel being used. Please see Appendices E-H for proper wiring
considerations.

14.3.6.2 Capacitive Type Fuel Quantity Sensors

The GSU 73 supports two frequency inputs for fuel quantity, the GEA 24 supports four frequency inputs
for fuel quantity.The P-300C receives a +5 V excitation input from the GEA 24/GSU 73 and outputs ±5 V
square wave from 600 Hz to 3.8 KHz. See
Capacitive fuel quantity sensors have either frequency or voltage-based ouputs. Capacitive sensors with
5 V or 12 V, 0-50 kHz frequency outputs (including the EI P-300C), are connected to the GEA 24/GSU 73
digital (frequency) fuel quantity inputs (CAP FUEL 1/2). Fuel quantity sensors with 0-5 VDC or 0-12
VDC analog outputs (such as the Skysports or Westach capacitive sensors), are connected to the GEA 24/
GSU 73 analog fuel quantity inputs (FUEL 1/2/3/4). See
NOTE
Vision Microsystems capacitive level senders may require installing a 5 kΩ pull-down
resistor at the sensor output.
NOTE
Princeton capacitive converters may require being connected to aircraft power as a
voltage source instead of using the 12V transducer power output.

14.3.7 TIT (Turbine Inlet Temperature) Sensor

Sensor Description – Type K grounded thermocouple probe with screw-in type adapter. This type of
sensor is applicable to all turbocharged engines.
General Installation Guidance – To maintain G3X Engine Indicating System (EIS) measurement
accuracy, thermocouple (TC) wire must be connected directly to the inputs of the GEA 24/GSU 73. If the
supplied sensor wires are not long enough to connect directly to the GEA 24/GSU 73, then Type K TC
extension wire must be used. To minimize risk of breakage, it is recommended that a high-quality stranded
(as opposed to solid) thermocouple wire be used. One such example of appropriate wire is TT-K-22S
Type K thermocouple wire from Omega Engineering.
14.3.8 Bus Voltage Monitor
Bus voltage is normally sensed from an external voltage signal connected to a GEA 24/GSU 73 analog
input (refer to Appendix E
measure bus voltage without requiring an external connection, by sensing the voltage of its power supply
inputs. See Section 18.3.2
G3X Installation Manual - Engine/Airframe Sensor Installation
Page 14-16
Appendix E
for interface drawings). Optionally, the GEA 24/GSU 73 can be configured to
(Volts 1 and Volts 2 Inputs) for configuration guidance.
for proper wiring considerations.
Figure E-2.1 for examples of each type.
190-01115-01
Rev. L