ICE AND RAIN PROTECTION
Operation
Aircraft Operations Manual
11.2
PAGE
7
Jun 01/19
CONDITIONS
NORMAL PROCEDURES
2.5
PROPELLER
DE
−
ICING
OPERATION
Propeller de
−
icing shall be used
−
As defined in icing conditions as defined for propeller de
−
ice operation
(see page 2)
In NORM mode when the temperature is between
−
5
C and
−
12
C SAT.
In MAX mode when the temperature is
−
13
C SAT or colder.
It is essential to use the correct propeller de
−
ice mode (NORM or MAX).
Turning on propeller de
−
ice in too warm temperature or using propeller de
−
ice in
wrong mode may cause performance degradation up to 30%.
CAUTION
Increased propeller RPM improves the ice shedding capabilities of propellers and
spinners. Therefore, select max PRPM if severe icing conditions are experienced
or expected.
NOTE
If unacceptable propeller vibrations occur in the temperature range
−
10
C to
−
12
C SAT due to propeller ice, use MAX mode. If unacceptable vibrations occur at
warmer temperatures than
−
10
C use MAX for a short period until the vibrations
disappear. Bear in mind the possibility of runback ice with subsequent perfor-
mance degradation if the system is continuously operating in MAX at SAT warmer
than
−
12
C. Switch to NORM as soon as possible.
NOTE
System check
1.
L/R PROP switches
NORMAL/MAX
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−
Leave L/R PROP switches in NORM for 60 seconds.
−
Check L/R PROP DE
−
ICE lights to come on.
2.
L/R PROP switches
OFF
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−
Check L/R PROP DE
−
ICE lights to go out.
When propeller de
−
ice required
When switching from NORMAL to MAX or MAX to NORMAL turn the switch to
OFF before selecting MAX respectively NORMAL. Switching direct from NOR-
MAL to MAX or vise versa may result in nuisance L/R PROP caution.
NOTE
(Cont’d)