ANTI-ICE AND DE-ICE SYSTEMS
61-00-75
Propeller Owner’s Manual
175
Page 7-4
Rev. 1
Jun/11
2. System Description
A. De-ice System
NOTE:
Because of the wide variances of various
de-ice systems, the following description is general
in nature. Consult the airframe manufacturer’s
manual for a description of your specific de-ice
system and controls.
The de-ice system is controlled by the pilot via a cockpit
control switch. This switch applies electrical power to the
de-ice system, which will operate as long as the switch is in
the ON position. Depending upon the system, another set
of cockpit controls may be available. One of these controls
is a mode selector, which
permits
the pilot to select two
cycling speeds, for heavy or light icing conditions. Some
systems on twin engine aircraft have a switch which provides
a full de-ice mode, which
permits
the pilot to de-ice both
propellers simultaneously. This switch may only be used for
short periods and is used when ice builds up on the propeller
before the system is turned on.
An ammeter, which indicates current drawn by the system,
is normally located near the de-ice system switches. This
meter may indicate total system load, or a separate meter
may be supplied for each propeller.
A timer, which is turned off and on by the cockpit control, is
used to sequence the de-ice system. This timer turns the
de-ice system on and off in proper sequence, controlling the
heating interval for each propeller and ensuring even
de-icing.
A brush block, which is mounted on the engine immediately
behind the propeller, supplies electrical current to the de-ice
boot on each propeller blade via a slip ring. The slip ring is
normally mounted on the spinner bulkhead.
When the pilot places the de-ice system cockpit control
switch in the ON position, system timer begins to operate.
As the timer sequences, power is delivered to a power relay.
The power relay delivers high current to the brush block and
slip ring. Each propeller is de-iced in turn by the timer.
OBSOLETE PROPELLER MODELS. SEE COVER PAGE
WARNINGS AND SERVICE BULLETIN HC-SB-61-331
