190-01115-01 G3X™/G3X Touch™ Avionics Installation Manual
Rev. AV Page 21-17
21.3 Engine Sensor Installation
NOTE
The following sections contain general guidance on engine and airframe sensor
installation. This information is provided for reference only. The installer should always
follow any installation guidance and instructions provided by the applicable engine,
sensor, or kit-plane manufacturer. Additionally, all installation practices should be done in
accordance with AC 43.13-1B.
Section 26
, Section 27, Section 28, and Section 29 contain interface drawings for sensor installations using
the Garmin sensor kits, and for other sensor installations.
21.3.1 CHT (Cylinder Head Temperature)
Both Type J and Type K grounded thermocouples are supported for cylinder head temperature (CHT)
measurements. Type K thermocouples are more commonly used for CHT.
To maintain measurement accuracy, appropriate thermocouple extension wire must be used to connect the
CHT probe sensor wires directly to the inputs of the GEA 24/GSU 73. To minimize risk of breakage, it is
recommended that a high-quality stranded (as opposed to solid) thermocouple wire be used. For Type K
thermocouples, one such example of appropriate wire is TT-K-22S Type K thermocouple wire from Omega
Engineering.
Thermocouple extension wire lengths may vary between cylinders for installation convenience; there is no
requirement to use the same length of thermocouple extension wire for each engine cylinder. However, for
each individual thermocouple lead, the positive and negative wires should be the same length. When
attaching thermocouple extension wire with splices or connectors, the connections for an individual pair of
positive/negative wires should be located close together to make sure they are exposed to similar ambient
temperatures.
NOTE
If ungrounded thermocouples are used, the low side must be connected to a GEA 24/
GSU 73 ground pin.
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