Document N° :
F2-1.0/R80/F/EU
Pioneer 200
Flight Manual
Section: 3
Emergency Procedures
REVISION :
0
Dated: 20-04-2002
Sect : 3 -Page: 12 of 124
3.4.1. CARBURETTOR
HEAT (IF APPLICABLE)
This system serves to prevent the formation of ice within the carburettor,
where it primarily forms on the throttle plates in such a manner as to
obstruct the airflow, with resultant eventual engine stoppage. Vaporisation
of the fuel & expansion of air through the carburettor cause a cooling of the
mixture, which can be as much as 15 degrees C below the temperature of
the ambient air. This permits moisture in the air to condense and form ice.
The first indications of icing are an RPM drop or a drop in manifold
pressure. Progressive icing will cause obstruction of the carburettor, which
manifests itself in the form of a rough running engine. During this time the
smaller volume of air aspirated has richened the mixture. Ice can form
more rapidly with partial throttle, due to the lower pressure in the
carburettor. At full throttle, the danger is lessened somewhat. Therefore,
carburettor heat is not to be used during takeoff or climb, also because it
creates a small power loss.
IMPORTANT
During descent & approach, the carburettor heat should be used because
low power settings create low pressures in the induction manifold. In case
of a go-around, turn the carburettor heat OFF. Prolonged use of carburettor
heat with more than 80% power applied could provoke detonation.
When using Carburettor Heat, pull knob to FULL ON.
DO NOT use partial Carburettor Heat.
Carburetor icing can occur when on the ground, particularly when the
aircraft and engine have become damp overnight. Check carburetor heat
during power check as normal, prior to lining up on runway close the
throttle completely, if a low tick over or engine stoppage occurs ice is
present so burn it off with twenty seconds of heat and then test again prior
to take off.
3.4.2. IGNITION
MALFUNCTION
A sudden engine roughness or misfiring is usually evidence of ignition
problems. Switching from both ON to alternately switching each system
OFF will identify which system is malfunctioning. Switch to the good
system and proceed to the nearest airport for repairs.
