AFMS N°D07 FOR GARMIN GFC700 AUTOPILOT AND VARIABLE PITCH PROPELLER EQUIPPED
AEROPLANES
Section 7 – Airframe and Systems description -
ENGINE CONTROLS
4.1
ENGINE CONTROL LEVER
Engine handling is via three levers: Throttle, RPM lever, Mixture control lever.
They‘re situated on the center control; the use of ―front/forward‖ and
―rear/backward‖ is defined in relation to the direction of flight (longitudinal).
Mixture control lever
This lever (right hand lever with red handle) controls the fuel-air mixture, which
is supplied to the engine.
With the lever full forward, extra fuel is being supplied to the engine which at
higher performance setting contributes to engine cooling.
In cruise, the mixture should be made leaner in order to reach the appropriate
fuel-air mixture. The leaning procedure is given in Chapter 4.
Lever forward (RICH) >> Mixture rich (in fuel)
Lever to rear (LEAN) >>Mixture lean (in fuel)
To shut off the engine the mixture control lever is pulled to the rear stop: air with-
out fuel is drawn into the cylinders that shuts down.
Throttle
This lever (left hand with large knob) is used to control manifold pressure (MAP).
High manifold pressure means a large quantity of fuel-air mixture is being sup-
plied to engine, while low manifold pressure means a lesser quantity of fuel-air
mixture is being supplied.
Propeller lever
By means of this lever (central lever with blue handle) the propeller governor
controls the propeller pitch, and consequently engine RPM. A selected RPM is
held constant by the governor independent of the airspeed and the throttle setting.
Lever forward (HIGH RPM) = fine pitch
Lever rearward (LOW RPM) = coarse pitch
Following a defect in governor or oil system, the blades go to the finest possible
pitch (maximum RPM), thus allowing continuation of the flight.
Following failure of the governor or a serious drop in oil pressure,
the RPM should be adjusted using the throttle. Every effort should
be made not to exceed 2700 RPM.
The throttle and RPM lever should be moved slowly, in order to
avoid over-speed and excessively rapid RPM changes.
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