Garmin GI 275 Installation Manual page 60

6. Fuel Quantity Sensor
The fuel quantity sensors must be either resistive float sensors with a resistance range between
25-620 Ω or CiES CC Series Fuel Senders. It is permissible to re-use existing fuel quantity wiring.
Extension splices are permissible. This STC does not approve alteration of the fuel tank wiring, fuel
tank equipment, or grounding provisions for the fuel system. For resistive fuel quantity sensors, the
maximum resistance of the tank must be no more than 620Ω, and the resistive range from full to empty
must be at least 25Ω. For resistive float sensors interfaced to the GEA 24, parallel resistors spliced
from the fuel excitation pin are required, and the sensor configuration must be set as 0-5 Volt sensors.
Refer to Appendix B for wiring diagrams and Appendix C for compatible part numbers. All CiES CC
Series Fuel Quantity Senders approved in STC SA02511SE are compatible.
7. Fuel Flow Sensor(s)
Select a fuel flow sensor that is approved under this STC listed in Appendix Section C.12 and suitable
for the engine horsepower and aircraft fuel supply type:
i. Electronics International FT-60 (Red Cube) - For aircraft with up to 350 HP and an engine-
driven fuel pump.
ii. Electronics International FT-90 (Gold Cube) - For aircraft with 350-550 HP or with gravity-
fed fuel systems.
The fuel flow sensor will introduce a small pressure drop. Refer to Appendix D to determine if a fuel
pressure test is required for a specific aircraft model. If required, the installer must perform the
Minimum Inlet Pressure Test as documented in AC 23-16 to ensure the minimum inlet fuel pressure
and a safety margin are available. Refer to AC 23-16, paragraph 23.955(a) for additional information
and procedures. If the AFM/POH has an operating limitation based only on fuel flow, the fuel flow
must be accurate within 10% to ensure the limitation is maintained. Refer to Section 6.5.3.6 for the
fuel flow check procedure, if it is required.
8. RPM Sensor
Methods for RPM sensing appropriate to the engine should be selected as follows:
1. P-lead sensor – One per magneto or two per dual magneto. Resistors must be installed in
accordance with Figure B-6.
2. Magneto vent mounted sensor – Not compatible with geared engines. One sensor for each
engine on non-pressurized magnetos only (e.g., Bendix -20, -21, -200, 1200 series, and Slick
6000, 4000 series).
190-02246-14
Rev. 11
GI 275 STC EIS & MFD Installation Manual
Page 3-18