Section 1 - General Information

1-1 Introduction

This manual provides complete information for the installation, operation, and maintenance of the ELLISON Throttle Body Injector (TBI).

This device offers improved aircraft engine performance and economy when installed and operated in accordance with this manual.

1-2 Description

The ELLISON Throttle Body Injector (TBI) is a variable venturi, diaphragm controlled, fuel metering device configured to supply the fuel and air requirements of several popular aircraft engines. It will operate in any attitude and through a wide range of G-loads, making it an attractive replacement for carburetors or fuel injectors.

1-3 Application

The ELLISON TBI is available in the five models listed in Table 1-3. Adjacent to each model is a list of engines having airflow and fuel flow requirements compatible with that model.

Table 1-3

1-4 Principles of Operation

The TBI shown in cut-away in figure 1-4 is a unique fuel metering in that fuel is injected in the plane of maximum airflow velocity, through a matrix of very small metering holes located in a tube extending across the entire width of the airflow passage. Fuel is admitted to this metering tube by a demand regulator, designed to maintain a slightly negative fuel pressure in the metering tube. The metering tube is positioned in a bore through the throttle slide. Movement of the throttle slide thereby controls fuel flow as well as airflow by changing the number of metering holes exposed to the air stream.

Figure 1-4

Rotation of the metering tube through a maximum angle of 90 degrees changes the orientation of the fuel metering holes with respect to the airflow. This rotation serves as the pilot's mixture control. Full lean occurs when the holes are facing directly into the on- coming airflow, and a progressively richer mixture is obtained as the holes are rotated away from the zero angle of attack position.

Because the fuel pressure in the metering tube is maintained below ambient pressure, fuel will not flow from the metering holes unless induction air is flowing through the inlet bore. This feature permits the engine to be shut down without the necessity of turning off the main fuel valve.

Idle fuel is dispensed by an idle fuel jet whose discharge rate is adjusted by a conventional needle valve located in the regulator end of the body.

1-5 Fuels Compatibility

The ELLISON TBI has been designed specifically for aircraft use and has been thoroughly tested with aviation fuels. Auto or agricultural fuels should NOT be used with the ELLISON TBI.

1-6 Performance Baseline

It is suggested that prior to beginning the installation of the TBI, the aircraft be flown through the flight test outlined in Section 5-1 of this manual steps 3 through 13 using the aircraft's original fuel metering system. Later comparison of this data with post-installation data will quantify the performance benefit or penalty resulting from the TBI installation.

In order to assure accuracy, it is very important that the test be flown in smooth air, preferably in the morning. It is also important that the aircraft be properly trimmed and allowed several minutes of hands-off level flight to stabilize its speed before any performance data is recorded.

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