Pilot Operating Handbook for the C42 Series
POH C42 SERIES ISSUE1 (B) REV7 25/04/2020
Page 29 of 73
4.9 Equipped with Optional Cowl Flap
If your aircraft is equipped with the cowl flap, you have a possibility to
control the temperatures of your engine via manual adjustment of the
cooling air.
There by, you are in the position to keep the engine temperatures in the
optimal range (90°-110°C) independent of outside temperatures. It works
in C42 both for the oil and cylinder head temperature and coolant
temperature due to the installed oil and water heat exchanger.
Moreover, you can considerably shorten warm-up period by starting up
the engine with a fully closed cowl flap.
It does not only protect the engine but also saves fuel. Though, for a
reasonable and secure handling of the cowl flap it is necessary to closely
monitor the oil and cylinder head temperature.
Attention:
If the cowl flap is closed the cooling air supply to the radiator
will not be sufficient over a longer period, i.e. the oil and cylinder head
temperature and coolant temperature will rise to an inadmissible range
(the red warning light range). In order to not to forget to close the cowl
flap, there will be installed an additional factory-provided warning light
which flashes up when reaching the cylinder head temperature and
coolant temperature of 117° C. In this case, the cowl flap should be
immediately fully opened.
The cooling down of the cylinder head temperature to admissive and
optimal temperatures can be supported by reducing the engine output
and increasing the airspeed in descending.
The functionality test of the cowl flap is made during pre-flight inspection.
Principally, you should not wait for flashing of the caution lamp, but you
have to observe the temperature and to open the cowl flap manually at
the temperature of 90°-110°.
