Electronics International CA-1 - Manual (Page 11)

8
Carburetor Temperature Operating Information
Continuous change in the CHT can also be a sign of trouble. Because of the large thermal mass of the
engine, the CHT’s change slowly after the initial climb. Any continuous change in one or all of the CHT’s
after this initial climb can be the sign of trouble. The rate and trend of this change can easily be detected
with Electronics International’s 1‘F resolution digital display. This information allows the pilot to make
changes in flight attitude or engine operation and see the effects almost instantaneously.
Carburetor Temperature
Venturi affect and atomization of fuel can cause temperatures in the carburetor to drop 30’F or more. When
the atmospheric conditions are right for the aircrafts’ current flight altitude (moderate to high humidity), the
moisture in the carburetor venturi can freeze quickly. Within minutes ice can choke off the venturi and the
engine will stop with little warning.
When Carb. Temp. is selected on the Electronics International Carb. Temp. instrument, the carburetor
temperature is continuously monitored and the “Ice Zone” warning light over the display is activated for that
channel. The “Ice Zone” warning light is only active for the channel selected. At 39’F (before ice can form
in the venturi of the carburetor) the “Ice Zone” warning light will light up. When this happens, apply carbu-
retor heat, making small adjustments to bring the carburetor temperature above 39’F, thereby avoiding any
possible carburetor icing condition. An additional benefit of running carburetor temperatures 9’F above
freezing is improved atomization of the fuel which results in fewer lead deposits, cleaner plugs and better
economy. If the carburetor temperature is below 10’F the “Ice Zone” warning light will go off. Below 10’F
there is not enough moisture in the air to form ice in the carburetor.
The “Ice Zone” warning light has the advantage of catching your attention without having to continuously
monitor the unit. At night this light may be too bright. An LED Intensity Control Line is provided which
may be connected to the aircraft panel rheostat. When the instrument panel lights are turned up the “Ice
Zone” warning light will dim.
Monitoring carburetor temperature to 1’F can also help with hard to start engines. If the engine becomes
flooded and fuel starts to drip from the carburetor, the unit will display a drop in carburetor temperature as
the fuel starts to evaporate. If the engine backfires and a fire starts in the venturi, the unit will display a rapid
rise in the carburetor temperature. The carburetor probe is rated for 700’F, so probe damage is not likely.
Outside Air Temperature
The Electronics International OAT instrument has three features that make it a valuable tool when measuring
outside air temperatures. The first of these features is its superior accuracy and linearity over conventional
gauges. Outside air temperatures have a big affect on your aircraft’s ability to lift and on engine horsepower.
Accurate OAT readings are essential if you are looking for maximum performance from your aircraft.