User manual

Section 4.1.1 Part B
03 ICING PREVENTION
It is preferable to take action to prevent icing rather than have to rely on more drastic de-
icing procedures once icing has occurred. When icing conditions are anticipated or
encountered:
A Set mixture control to Auto Rich
B Apply preheat to maintain 32 degC (or up to 38 degC maximum)
carburetor air temperature.
C After carburetor air temperature and engine operation have stabilized,
adjust mixture to desired setting.
D In flight, it is best to use preheat at least 15 minutes before entering
known or anticipated icing conditions. Preheat is most effective at
preventing of icing (and accompanying power loss) if applied and
maintained well in advance of encountering these conditions. As a
precaution therefore, when atmospheric conditions are conducive to
the formation of carburetor ice, it is recommended to cruise with the
preheat control set to maintain between 15 -25 degC carburetor temp,
and to be prepared to increase the temperature to 32 degC (38 degC
Maximum) if required.
E To prevent icing during take-off, maintain 32 degC to 38 degC
carburetor air temperature during warm-up and ground running, but
set Carb heat COLD several minutes before take-off. Keep carb heat
COLD for take-off and be ready to apply 32 degC (or up to 38 degC
maximum) carburetor air temperature for ice protection during climb
04 ICING INDICATORS
When operating in icing conditions without carburetor heat, there may be little warning that
icing has occurred until it has produced sufficient ice to seriously impair engine
performance. The following indications may accompany icing:
A Decreasing power and airspeed at constant throttle and APM, either
with or without an accompanying decrease in Manifold Pressure. If
there is no decrease in manifold pressure, the power loss is probably
due to leaning or enrichment of the mixture. If there is a reduction in
manifold pressure, the power loss is probably due to restricted airflow
through the induction system.
B A rapid loss of power, possibly accompanied by rough or erratic
engine operation, indicates severe leaning or enrichment of the
carburetor
C Uneven response of manifold pressure to changed throttle settings
may occur due to ice jamming or sticking the carburetor throttle.
D Erratic engine operation due to ice on metering elements, with
resulting changes in mixture or mixture distribution to the cylinders.
Rev No: 00 Stichting Catalina PH-PBY
Page: 2 18 May, 2004